Selective transporter that mediates the uptake of Zn(2+) (PubMed:17202136, PubMed:22242765, PubMed:27321477, PubMed:28875161, PubMed:31164399, PubMed:31914589, PubMed:31979155, PubMed:33837739, PubMed:36473915). Plays an essential role for dietary zinc uptake from small intestine (By similarity). The Zn(2+) uniporter activity is regulated by zinc availability (PubMed:17202136, PubMed:32348750). Also exhibits polyspecific binding and transport of Cu(2+), Cd(2+) and possibly Ni(2+) but at higher c

Cell membraneRecycling endosome membraneApical cell membrane

Acrodermatitis enteropathica, zinc-deficiency type

A rare autosomal recessive disease caused by the inability to absorb sufficient zinc. The clinical features are growth retardation, immune-system dysfunction, alopecia, severe dermatitis, diarrhea and occasionally mental disorders.

Forms paracellular channels: coassembles with CLDN16 into tight junction strands with cation-selective channels through the strands, conveying epithelial permeability in a process known as paracellular tight junction permeability (PubMed:18188451, PubMed:28028216). Involved in the maintenance of ion gradients along the nephron. In the thick ascending limb (TAL) of Henle's loop, facilitates sodium paracellular permeability from the interstitial compartment to the lumen, contributing to the lumen-

Cell junction, tight junctionCell membrane

Hypomagnesemia 5, renal, with or without ocular involvement

A progressive renal disease characterized by primary renal magnesium wasting with hypomagnesemia, hypercalciuria and nephrocalcinosis associated with severe ocular abnormalities such as bilateral chorioretinal scars, macular colobomata, significant myopia and nystagmus. The renal phenotype is virtually undistinguishable from that of patients with HOMG3.

Forms paracellular channels: coassembles with CLDN19 into tight junction strands with cation-selective channels through the strands, conveying epithelial permeability in a process known as paracellular tight junction permeability (PubMed:16234325, PubMed:18188451, PubMed:28028216). Involved in the maintenance of ion gradients along the nephron. In the thick ascending limb (TAL) of Henle's loop, facilitates sodium paracellular permeability from the interstitial compartment to the lumen, contribut

Cell junction, tight junctionCell membrane

Hypomagnesemia 3

A progressive renal disease characterized by primary renal magnesium wasting with hypomagnesemia, hypercalciuria and nephrocalcinosis. Recurrent urinary tract infections and kidney stones are often observed. In spite of hypercalciuria, patients do not show hypocalcemia.

Acts as a bone morphogenetic protein (BMP) coreceptor (PubMed:18976966). Through enhancement of BMP signaling regulates hepcidin (HAMP) expression and regulates iron homeostasis (PubMed:18976966)

Cell membrane

Hemochromatosis 2A

A juvenile form of hemochromatosis, a disorder of iron metabolism with excess deposition of iron in a variety of organs leading to their failure, bronze skin pigmentation, hepatic cirrhosis, arthropathy and diabetes. The most common symptoms of juvenile hemochromatosis at presentation are hypogonadism and cardiomyopathy.

Thiol-specific peroxidase that catalyzes the reduction of hydrogen peroxide and organic hydroperoxides to water and alcohols, respectively. Plays a role in cell protection against oxidative stress by detoxifying peroxides and as sensor of hydrogen peroxide-mediated signaling events. Might participate in the signaling cascades of growth factors and tumor necrosis factor-alpha by regulating the intracellular concentrations of H(2)O(2) (PubMed:9497357). Reduces an intramolecular disulfide bond in G

CytoplasmMelanosome

Lysosomal membrane protein that transports cobalamin (Vitamin B12) from the lysosomal lumen to the cytosol in an ATP-dependent manner (PubMed:22922874, PubMed:28572511, PubMed:31467407, PubMed:33845046). Targeted by LMBRD1 lysosomal chaperone from the endoplasmic reticulum to the lysosomal membrane (PubMed:27456980). Then forms a complex with lysosomal chaperone LMBRD1 and cytosolic MMACHC to transport cobalamin across the lysosomal membrane (PubMed:25535791)

Endoplasmic reticulum membraneLysosome membrane

Methylmalonic aciduria and homocystinuria type cblJ

A disorder of cobalamin metabolism characterized by decreased levels of the coenzymes adenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl). Clinical features include feeding difficulties, poor growth, hypotonia, lethargy, anemia, and developmental delay.

Mitochondrial proton-coupled zinc ion antiporter mediating the export of zinc from the mitochondria and involved in zinc homeostasis, zinc mobilization as well as mitochondrial morphology and health (PubMed:28334855, PubMed:34397090, PubMed:34433664, PubMed:35614220). In nucleus, functions as a secondary coactivator for nuclear receptors by cooperating with p160 coactivators subtypes. Plays a role in transcriptional activation of Wnt-responsive genes (By similarity)

Mitochondrion membraneNucleusEndoplasmic reticulum

Birk-Landau-Perez syndrome

An autosomal recessive syndrome characterized by early-childhood onset of different combinations of intellectual disability, muscle weakness, camptocormia, oculomotor apraxia, and nephropathy.

Catalyzes the transfer of a methyl group from methylcob(III)alamin (MeCbl) to homocysteine, yielding enzyme-bound cob(I)alamin and methionine in the cytosol (PubMed:16769880, PubMed:17288554, PubMed:27771510). MeCbl is an active form of cobalamin (vitamin B12) used as a cofactor for methionine biosynthesis. Cob(I)alamin form is regenerated to MeCbl by a transfer of a methyl group from 5-methyltetrahydrofolate (PubMed:16769880, PubMed:17288554, PubMed:27771510). The processing of cobalamin in the

Cytoplasm

Homocystinuria-megaloblastic anemia, cblG type

An autosomal recessive inborn error of metabolism resulting from defects in the cobalamin-dependent pathway that converts homocysteine to methionine. It causes delayed psychomotor development, megaloblastic anemia, homocystinuria, and hypomethioninemia.

Symmetrically cleaves beta-carotene into two molecules of retinal using a dioxygenase mechanism

Cytoplasm, cytosol

Hypercarotenemia and vitamin A deficiency, autosomal dominant

A disorder characterized by increased serum beta-carotene, decreased conversion of beta-carotene to vitamin A and decreased serum vitamin A.

Converts cob(I)alamin to adenosylcobalamin (adenosylcob(III)alamin), a coenzyme for methylmalonyl-CoA mutase, therefore participates in the final step of the vitamin B12 conversion (PubMed:12514191). Generates adenosylcobalamin (AdoCbl) and directly delivers the cofactor to MUT in a transfer that is stimulated by ATP-binding to MMAB and gated by MMAA (Probable)

Mitochondrion

Methylmalonic aciduria, cblB type

An autosomal recessive disorder of methylmalonate and cobalamin metabolism due to defective synthesis of adenosylcobalamin.

Copper ion transmembrane transporter involved in the export of copper out of the cells. It is involved in copper homeostasis in the liver, where it ensures the efflux of copper from hepatocytes into the bile in response to copper overload

Golgi apparatus, trans-Golgi network membraneLate endosomeGolgi apparatus membraneCytoplasmMitochondrion

Wilson disease

An autosomal recessive disorder of copper metabolism in which copper cannot be incorporated into ceruloplasmin in liver, and cannot be excreted from the liver into the bile. Copper accumulates in the liver and subsequently in the brain and kidney. The disease is characterized by neurologic manifestations and signs of cirrhosis.

Cobalamin (vitamin B12) cytosolic chaperone that catalyzes the reductive decyanation of cyanocob(III)alamin (cyanocobalamin, CNCbl) to yield cob(II)alamin and cyanide, using FAD or FMN as cofactors and NADPH as cosubstrate (PubMed:18779575, PubMed:19700356, PubMed:21697092, PubMed:25809485). Cyanocobalamin constitutes the inactive form of vitamin B12 introduced from the diet, and is converted into the active cofactors methylcobalamin (MeCbl) involved in methionine biosynthesis, and 5'-deoxyadeno

Cytoplasm, cytosol

Methylmalonic aciduria and homocystinuria, cblC type

An autosomal recessive disorder of cobalamin metabolism characterized by decreased levels of the coenzymes adenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl). Affected individuals may have developmental, hematologic, neurologic, metabolic, ophthalmologic, and dermatologic clinical findings. Although considered a disease of infancy or childhood, some individuals develop symptoms in adulthood.

Binds to folate and reduced folic acid derivatives and mediates delivery of 5-methyltetrahydrofolate and folate analogs into the interior of cells (PubMed:19074442, PubMed:23851396, PubMed:23934049, PubMed:2527252, PubMed:8033114, PubMed:8567728). Has high affinity for folate and folic acid analogs at neutral pH (PubMed:23851396, PubMed:23934049, PubMed:2527252, PubMed:8033114, PubMed:8567728). Exposure to slightly acidic pH after receptor endocytosis triggers a conformation change that strongly

Cell membraneApical cell membraneBasolateral cell membraneSecretedCytoplasmic vesicleCytoplasmic vesicle, clathrin-coated vesicleEndosome

Neurodegeneration due to cerebral folate transport deficiency

An autosomal recessive neurodegenerative disorder resulting from brain-specific folate deficiency early in life. Onset is apparent in late infancy with severe developmental regression, movement disturbances, epilepsy and leukodystrophy.

Transports Fe(2+) from the inside of a cell to the outside of the cell, playing a key role for maintaining systemic iron homeostasis (PubMed:15692071, PubMed:22178646, PubMed:22682227, PubMed:24304836, PubMed:29237594, PubMed:29599243, PubMed:30247984). Transports iron from intestinal, splenic, hepatic cells, macrophages and erythrocytes into the blood to provide iron to other tissues (By similarity). Controls therefore dietary iron uptake, iron recycling by macrophages and erythrocytes, and rel

Cell membraneBasolateral cell membrane

Hemochromatosis 4

A disorder of iron metabolism characterized by iron overload. Excess iron is deposited in a variety of organs leading to their failure, and resulting in serious illnesses including cirrhosis, hepatomas, diabetes, cardiomyopathy, arthritis, and hypogonadotropic hypogonadism. Severe effects of the disease usually do not appear until after decades of progressive iron loading.

Folate-dependent enzyme, that displays both transferase and deaminase activity. Serves to channel one-carbon units from formiminoglutamate to the folate pool Binds and promotes bundling of vimentin filaments originating from the Golgi

Cytoplasm, cytosolGolgi apparatusCytoplasm, cytoskeleton, microtubule organizing center, centrosome, centriole

Glutamate formiminotransferase deficiency

Autosomal recessive disorder. Features of a severe phenotype, include elevated levels of formiminoglutamate (FIGLU) in the urine in response to histidine administration, megaloblastic anemia, and intellectual disability. Features of a mild phenotype include high urinary excretion of FIGLU in the absence of histidine administration, mild developmental delay, and no hematological abnormalities.

May be involved in forming the receptor site for cardiac glycoside binding or may modulate the transport function of the sodium ATPase

Membrane

Hypomagnesemia 2

A disorder due to primary renal wasting of magnesium. Plasma levels of other electrolytes are normal. The only abnormality found, in addition to low magnesium levels, is lowered renal excretion of calcium resulting in hypocalciuria.

Key enzyme in methionine and folate homeostasis responsible for the reactivation of methionine synthase (MTR/MS) activity by catalyzing the reductive methylation of MTR-bound cob(II)alamin (PubMed:17892308). Cobalamin (vitamin B12) forms a complex with MTR to serve as an intermediary in methyl transfer reactions that cycles between MTR-bound methylcob(III)alamin and MTR bound-cob(I)alamin forms, and occasional oxidative escape of the cob(I)alamin intermediate during the catalytic cycle leads to

Cytoplasm

Homocystinuria-megaloblastic anemia, cblE type

An autosomal recessive inborn error of metabolism resulting from defects in the cobalamin-dependent pathway that converts homocysteine to methionine. It causes delayed psychomotor development, megaloblastic anemia, homocystinuria, and hypomethioninemia. Cells from patients with HMAE fail to incorporate methyltetrahydrofolate into methionine in whole cells, but cell extracts show normal methionine synthase activity in the presence of a reducing agent.

Bifunctional protein that combines an ion channel with an intrinsic kinase domain, enabling it to modulate cellular functions either by conducting ions through the pore or by phosphorylating downstream proteins via its kinase domain (PubMed:14576148, PubMed:16636202, PubMed:18258429, PubMed:18365021). Crucial for Mg(2+) homeostasis. Has an important role in epithelial Mg(2+) transport and in the active Mg(2+) absorption in the gut and kidney (PubMed:14576148). However, whether TRPM6 forms functi

Cell membraneApical cell membraneNucleus

Hypomagnesemia 1

A disorder due to a primary defect in intestinal magnesium absorption. It is characterized by low levels of serum magnesium alongside with a normal renal magnesium secretion, secondary hypocalcemia and calcinocis. Affected individuals show neurologic symptoms of hypomagnesemic hypocalcemia, including seizures and muscle spasms, during infancy. Hypocalcemia is secondary to parathyroid failure resulting from magnesium deficiency. Untreated, the disorder may be fatal or may result in neurological damage.

Stores iron in a soluble, non-toxic, readily available form. Important for iron homeostasis. Has ferroxidase activity (PubMed:9003196). Iron is taken up in the ferrous form and deposited as ferric hydroxides after oxidation (PubMed:9003196). Also plays a role in delivery of iron to cells (By similarity). Mediates iron uptake in capsule cells of the developing kidney (By similarity). Delivery to lysosomes is mediated by the cargo receptor NCOA4 for autophagic degradation and release of iron (PubM

CytoplasmLysosomeCytoplasmic vesicle, autophagosome

Hemochromatosis 5

A disorder of iron metabolism characterized by iron overload. Excess iron is deposited in a variety of organs leading to their failure, and resulting in serious illnesses including cirrhosis, hepatomas, diabetes, cardiomyopathy, arthritis, and hypogonadotropic hypogonadism. Severe effects of the disease usually do not appear until after decades of progressive iron loading.

Membrane-bound component of the endocytic receptor formed by AMN and CUBN (PubMed:14576052, PubMed:29402915, PubMed:30523278). Required for normal CUBN glycosylation and trafficking to the cell surface (PubMed:14576052, PubMed:29402915). The complex formed by AMN and CUBN is required for efficient absorption of vitamin B12 (PubMed:12590260, PubMed:14576052, PubMed:26040326). Required for normal CUBN-mediated protein transport in the kidney (Probable)

Apical cell membraneCell membraneEndosome membraneMembrane, coated pitSecreted

Imerslund-Grasbeck syndrome 2

A form of Imerslund-Grasbeck syndrome, a rare autosomal recessive disorder characterized by vitamin B12 deficiency commonly resulting in megaloblastic anemia, which is responsive to parenteral vitamin B12 therapy and appears in infancy or early childhood. Clinical manifestations include failure to thrive, infections and neurological damage. Mild proteinuria, with no signs of kidney disease, is present in about half of the patients.

Mitochondrial transporter mediating uptake of thiamine diphosphate into mitochondria. It is not clear if the antiporter activity is affected by the membrane potential or by the proton electrochemical gradient

Mitochondrion membrane

Microcephaly, Amish type

A disorder characterized by severe congenital microcephaly and severe 2-ketoglutaric aciduria leading to death within the first year.

Binds to transferrin receptor (TFR) and reduces its affinity for iron-loaded transferrin

Cell membrane

Hemochromatosis 1

A disorder of iron metabolism characterized by iron overload. Excess iron is deposited in a variety of organs leading to their failure, and resulting in serious illnesses including cirrhosis, hepatomas, diabetes, cardiomyopathy, arthritis, and hypogonadotropic hypogonadism. Severe effects of the disease usually do not appear until after decades of progressive iron loading.

Subunit of clathrin-associated adaptor protein complex 1 that plays a role in protein sorting in the late-Golgi/trans-Golgi network (TGN) and/or endosomes (PubMed:31630791). The AP complexes mediate both the recruitment of clathrin to membranes and the recognition of sorting signals within the cytosolic tails of transmembrane cargo molecules

Golgi apparatusCytoplasmic vesicle, clathrin-coated vesicle membrane

Keratitis-ichthyosis-deafness syndrome, autosomal recessive

An autosomal recessive form of keratitis-ichthyosis-deafness syndrome, a disease characterized by the association of hyperkeratotic skin lesions with vascularizing keratitis and profound sensorineural hearing loss. KIDAR patients manifest ichthyosis, failure to thrive and developmental delay in childhood, thrombocytopenia, photophobia, and progressive hearing loss. Low plasma copper and ceruloplasmin levels have been reported in some patients.

Guanine nucleotide-binding protein that plays a crucial role in the cellular response to amino acid availability through regulation of the mTORC1 signaling cascade (PubMed:20381137, PubMed:24095279, PubMed:34607910). Forms heterodimeric Rag complexes with RagA/RRAGA or RagB/RRAGB and cycles between an inactive GTP-bound and an active GDP-bound form: RagD/RRAGD is in its active form when GDP-bound RagD/RRAGD forms a complex with GTP-bound RagA/RRAGA (or RagB/RRAGB) and in an inactive form when GT

CytoplasmNucleusLysosome membrane

Hypomagnesemia 7, renal, with or without dilated cardiomyopathy

An autosomal dominant renal disease characterized by hypomagnesemia, hypokalemia, salt wasting, and nephrocalcinosis. A subset of patients develop severe dilated cardiomyopathy.

Catalyzes the reduction of 7,8-dihydrofolate (DHF) to 5,6,7,8-tetrahydrofolate in a NADPH-dependent manner (PubMed:12096917, PubMed:15039552, PubMed:17569517, PubMed:19196009, PubMed:19478082, PubMed:21876184, PubMed:9719595). Key enzyme in folate metabolism. Contributes to the nuclear and mitochondrial de novo thymidylate biosynthesis pathway (PubMed:21876188, PubMed:22235121). Catalyzes an essential reaction for de novo glycine and purine synthesis, and for DNA precursor synthesis. Binds its o

MitochondrionCytoplasmNucleus

Megaloblastic anemia due to dihydrofolate reductase deficiency

An inborn error of metabolism, characterized by megaloblastic anemia and/or pancytopenia, severe cerebral folate deficiency, and cerebral tetrahydrobiopterin deficiency. Clinical features include variable neurologic symptoms, ranging from severe developmental delay and generalized seizures in infancy, to childhood absence epilepsy with learning difficulties, to lack of symptoms.

Membrane

Transferrins are iron binding transport proteins which can bind two Fe(3+) ions in association with the binding of an anion, usually bicarbonate. It is responsible for the transport of iron from sites of absorption and heme degradation to those of storage and utilization. Serum transferrin may also have a further role in stimulating cell proliferation (Microbial infection) Serves as an iron source for Neisseria species, which capture the protein and extract its iron for their own use (Microbial

Secreted

Atransferrinemia

A rare autosomal recessive disorder characterized by abnormal synthesis of transferrin leading to iron overload and microcytic hypochromic anemia.

Mediates cellular uptake of transferrin-bound iron in a non-iron dependent manner. May be involved in iron metabolism, hepatocyte function and erythrocyte differentiation

Cell membraneCytoplasm

Hemochromatosis 3

A disorder of iron metabolism characterized by iron overload. Excess iron is deposited in a variety of organs leading to their failure, and resulting in serious illnesses including cirrhosis, hepatomas, diabetes, cardiomyopathy, arthritis, and hypogonadotropic hypogonadism. Severe effects of the disease usually do not appear until after decades of progressive iron loading.

Subunit of clathrin-associated adaptor protein complex 1 that plays a role in protein sorting in the late-Golgi/trans-Golgi network (TGN) and/or endosomes. The AP complexes mediate both the recruitment of clathrin to membranes and the recognition of sorting signals within the cytosolic tails of transmembrane cargo molecules

Golgi apparatusCytoplasmic vesicle membraneMembrane, clathrin-coated pit

MEDNIK syndrome

A disorder characterized by erythematous skin lesions and hyperkeratosis, severe psychomotor retardation, peripheral neuropathy, sensorineural hearing loss, together with elevated very-long-chain fatty acids and severe congenital diarrhea.

Stores iron in a soluble, non-toxic, readily available form. Important for iron homeostasis. Iron is taken up in the ferrous form and deposited as ferric hydroxides after oxidation. Also plays a role in delivery of iron to cells. Mediates iron uptake in capsule cells of the developing kidney (By similarity). Delivery to lysosomes by the cargo receptor NCOA4 for autophagic degradation and release or iron (PubMed:24695223)

Cytoplasmic vesicle, autophagosomeCytoplasmAutolysosome

Hyperferritinemia with or without cataract

An autosomal dominant disease characterized by elevated level of ferritin in serum and tissues, and early-onset bilateral cataract. Cataracts may be subclinical in some patients.

Catalyzes the phosphorylation of thiamine to thiamine pyrophosphate (TPP) utilizing UTP and therefore links the biosynthesis of TPP to pyrimidines metabolism (PubMed:38547260). By producing thiamine pyrophosphate, a cofactor of the mitochondrial pyruvate dehydrogenase indirectly regulates pyruvate oxidation and lipogenesis (PubMed:38547260). Although it can also catalyze thiamine phosphorylation using ATP and CTP in vitro, it does so with significantly lower efficiency and without physiological

Thiamine metabolism dysfunction syndrome 5, episodic encephalopathy type

An autosomal recessive metabolic disorder due to an inborn error of thiamine metabolism. The phenotype is highly variable, but in general, affected individuals have onset in early childhood of acute encephalopathic episodes associated with increased serum and CSF lactate. These episodes result in progressive neurologic dysfunction manifest as gait disturbances, ataxia, dystonia, and spasticity, which in some cases may result in loss of ability to walk. Cognitive function is usually preserved, although mildly delayed development has been reported. These episodes are usually associated with infection and metabolic decompensation. Some patients may have recovery of some neurologic deficits.

Transcriptional coregulator (By similarity). Serves as a scaffold protein, bridging interactions between transcription factors, including THAP11 and ZNF143, and transcriptional coregulators (PubMed:26416877). Involved in control of the cell cycle (PubMed:10629049, PubMed:10779346, PubMed:15190068, PubMed:16624878, PubMed:23629655). Also antagonizes transactivation by ZBTB17 and GABP2; represses ZBTB17 activation of the p15(INK4b) promoter and inhibits its ability to recruit p300 (PubMed:10675337

CytoplasmNucleus

Methylmalonic aciduria and homocystinuria, cblX type

An X-linked recessive metabolic disorder characterized by severely delayed psychomotor development apparent in infancy, failure to thrive, impaired intellectual development, and intractable epilepsy. Additional features may include microcephaly and choreoathetosis.

Divalent metal cation transporter. Mediates transport of divalent metal cations in an order of Mg(2+) > Co(2+) > Mn(2+) > Sr(2+) > Ba(2+) > Cu(2+) > Fe(2+) (By similarity)

Cell membrane

Hypomagnesemia 6

A renal disease characterized by severely lowered serum magnesium levels in the absence of other electrolyte disturbances. Affected individuals show an inappropriately normal urinary magnesium excretion, demonstrating a defect in tubular reabsorption. Age of clinical onset is highly variable and some affected individuals are asymptomatic.

Lysosomal membrane chaperone required to export cobalamin (vitamin B12) from the lysosome to the cytosol, allowing its conversion to cofactors (PubMed:19136951). Targets ABCD4 transporter from the endoplasmic reticulum to the lysosome (PubMed:27456980). Then forms a complex with lysosomal ABCD4 and cytoplasmic MMACHC to transport cobalamin across the lysosomal membrane (PubMed:25535791). Acts as an adapter protein which plays an important role in mediating and regulating the internalization of t

Endoplasmic reticulum membraneLysosome membraneCell membraneCytoplasmic vesicle, clathrin-coated vesicle

Methylmalonic aciduria and homocystinuria, cblF type

An autosomal recessive disorder of cobalamin metabolism characterized by decreased levels of the coenzymes adenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl). It is due to accumulation of free cobalamin in lysosomes, thus hindering its conversion to cofactors. Clinical features include developmental delay, stomatitis, glossitis, seizures and methylmalonic aciduria responsive to vitamin B12.

Electroneutral transporter of the plasma membrane mediating the cellular uptake of the divalent metal cations zinc, manganese and iron that are important for tissue homeostasis, metabolism, development and immunity (PubMed:15642354, PubMed:27231142, PubMed:29621230). Functions as an energy-dependent symporter, transporting through the membranes an electroneutral complex composed of a divalent metal cation and two bicarbonate anions (By similarity). Beside these endogenous cellular substrates, ca

Cell membraneApical cell membraneBasolateral cell membraneEarly endosome membraneLate endosome membraneLysosome membrane

Hypermanganesemia with dystonia 2

A metabolic autosomal recessive disorder characterized by increased blood manganese levels, neurodegeneration, and rapidly progressive parkinsonism and dystonia. Affected individuals present with loss of developmental milestones, progressive dystonia and bulbar dysfunction in infancy or early childhood. Towards the end of the first decade, they manifest severe generalized pharmacoresistant dystonia, spasticity, limb contractures and scoliosis, and loss of independent ambulation. Cognition may be impaired, but is better preserved than motor function.

Calcium:manganese antiporter of the plasma membrane mediating the efflux of intracellular manganese coupled to an active extracellular calcium exchange (PubMed:30755481). Required for intracellular manganese homeostasis, an essential cation for the function of several enzymes, including some crucially important for the metabolism of neurotransmitters and other neuronal metabolic pathways. Manganese can also be cytotoxic and induce oxidative stress, mitochondrial dysfunction and apoptosis (PubMed

Cell membraneGolgi apparatus membraneRecycling endosome membraneEarly endosome membrane

Hypermanganesemia with dystonia 1

A metabolic autosomal recessive disorder characterized by dystonia, parkinsonism, extrapyramidal signs, severe hypermanganesemia, polycythemia, and chronic hepatic disease, including steatosis and cirrhosis.

Receptor for transcobalamin saturated with cobalamin (TCbl) (PubMed:18779389). Plays an important role in cobalamin uptake (PubMed:18779389, PubMed:20524213). Plasma membrane protein that is expressed on follicular dendritic cells (FDC) and mediates interaction with germinal center B cells (PubMed:10727470). Functions as costimulator to promote B cell responses to antigenic stimuli; promotes B cell differentiation and proliferation (PubMed:10727470, PubMed:11418631). Germinal center-B (GC-B) cel

Cell membrane

Methylmalonic aciduria, transient, due to transcobalamin receptor defect

An autosomal recessive metabolic condition characterized by moderate methymalonicaciduria, and normal plasma vitamin B12 levels. Serum homocysteine may be increased in some affected individuals. Most cases are clinically asymptomatic.

Promotes absorption of the essential vitamin cobalamin (Cbl) in the ileum. After interaction with CUBN, the CBLIF-cobalamin complex is internalized via receptor-mediated endocytosis

Secreted

Hereditary intrinsic factor deficiency

Autosomal recessive disorder characterized by megaloblastic anemia.

Multifunctional blue, copper-binding (6-7 atoms per molecule) glycoprotein. It has ferroxidase activity oxidizing Fe(2+) to Fe(3+) without releasing radical oxygen species. It is involved in iron transport across the cell membrane (PubMed:16150804). Copper ions provide a large number of enzymatic activites. Oxidizes highly toxic ferrous ions to the ferric state for further incorporation onto apo-transferrins, catalyzes Cu(+) oxidation and promotes the oxidation of biogenic amines such as norepin

Secreted

Aceruloplasminemia

An autosomal recessive disorder of iron metabolism characterized by iron accumulation in the brain as well as visceral organs. Clinical features consist of the triad of retinal degeneration, diabetes mellitus and neurological disturbances.

Contributes to tetrahydrofolate metabolism. Helps regulate carbon flow through the folate-dependent one-carbon metabolic network that supplies carbon for the biosynthesis of purines, thymidine and amino acids. Catalyzes the irreversible conversion of 5-formyltetrahydrofolate (5-FTHF) to yield 5,10-methenyltetrahydrofolate

Cytoplasm

Neurodevelopmental disorder with microcephaly, epilepsy, and hypomyelination

An autosomal recessive neurodevelopmental disorder with onset at birth or in early infancy, and characterized by microcephaly, short stature, severe global developmental delay, progressive spasticity, and epilepsy. Brain imaging shows delayed myelination, hypomyelination, enlarged ventricles, and cerebellar atrophy.

Transcription factor, which has both transcriptional activation and repression activities (PubMed:31905202). Also modulates chromatin accessibility (PubMed:38361031). In complex with HCFC1 and ZNF143, regulates the expression of several genes, including AP2S1, ESCO2, OPHN1, RBL1, UBXN8 and ZNF32 (PubMed:26416877). May regulate the expression of genes that encode both cytoplasmic and mitochondrial ribosomal proteins (By similarity). Required for normal mitochondrial development and function. Regu

NucleusCytoplasm

Methylmalonic aciduria and homocystinuria type cblL

An autosomal recessive disorder of cobalamin metabolism clinically characterized by early-onset seizures, and profound global developmental delay with severe intellectual disability. Metabolic features are mild methylmalonic aciduria, low-normal plasma methionine, and high-normal plasma homocysteine.

Plasma membrane transporter mediating the uptake by cells of the water soluble vitamin B2/riboflavin that plays a key role in biochemical oxidation-reduction reactions of the carbohydrate, lipid, and amino acid metabolism (PubMed:18632736, PubMed:20463145). Humans are unable to synthesize vitamin B2/riboflavin and must obtain it via intestinal absorption (PubMed:20463145) (Microbial infection) May function as a cell receptor to retroviral envelopes similar to the porcine endogenous retrovirus (P

Cell membrane

Riboflavin deficiency

A disorder caused by a primary defect in riboflavin metabolism, or by dietary riboflavin deficiency. Riboflavin deficiency during pregnancy results in hypoglycemia, metabolic acidosis, dicarboxylic aciduria and elevated plasma acylcarnitine levels in the newborn. Treatment with oral riboflavin results in complete resolution of the clinical and biochemical findings.

This is the catalytic component of the active enzyme, which catalyzes the hydrolysis of ATP coupled with the exchange of sodium and potassium ions across the plasma membrane. This action creates the electrochemical gradient of sodium and potassium ions, providing the energy for active transport of various nutrients (PubMed:29499166, PubMed:30388404). Could also be part of an osmosensory signaling pathway that senses body-fluid sodium levels and controls salt intake behavior as well as voluntary

Cell membraneBasolateral cell membraneCell membrane, sarcolemmaCell projection, axonMelanosome

Charcot-Marie-Tooth disease, axonal, type 2DD

A dominant axonal form of Charcot-Marie-Tooth disease, a disorder of the peripheral nervous system, characterized by progressive weakness and atrophy, initially of the peroneal muscles and later of the distal muscles of the arms. Charcot-Marie-Tooth disease is classified in two main groups on the basis of electrophysiologic properties and histopathology: primary peripheral demyelinating neuropathies (designated CMT1 when they are dominantly inherited) and primary peripheral axonal neuropathies (CMT2). Neuropathies of the CMT2 group are characterized by signs of axonal degeneration in the absence of obvious myelin alterations, normal or slightly reduced nerve conduction velocities, and progressive distal muscle weakness and atrophy.

Involved in cobalamin metabolism and trafficking (PubMed:18385497, PubMed:23415655, PubMed:24722857, PubMed:26364851). Plays a role in regulating the biosynthesis and the proportion of two coenzymes, methylcob(III)alamin (MeCbl) and 5'-deoxyadenosylcobalamin (AdoCbl) (PubMed:18385497, PubMed:23415655, PubMed:24722857). Promotes oxidation of cob(II)alamin bound to MMACHC (PubMed:26364851). The processing of cobalamin in the cytosol occurs in a multiprotein complex composed of at least MMACHC, MMA

CytoplasmMitochondrion

Methylmalonic aciduria and homocystinuria, cblD type

An autosomal recessive disorder of cobalamin metabolism characterized by decreased levels of the coenzymes adenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl). Clinical features include developmental delay, hyotonia, intellectual disability, seizures, and megaloblastic anemia. Laboratory studies show methylmalonic aciduria and homocystinuria.

Catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, a cosubstrate for homocysteine remethylation to methionine (PubMed:29891918). Represents a key regulatory connection between the folate and methionine cycles (Probable)

Homocystinuria due to deficiency of N(5,10)-methylenetetrahydrofolate reductase activity

An autosomal recessive inborn error of folate metabolism. Clinical severity is variable, ranging from severe neurologic features to absence of symptoms. Clinical features include homocysteinuria, homocysteinemia, developmental delay, severe intellectual disability, perinatal death, psychiatric disturbances, and later-onset neurodegenerative disorders.

High-affinity transporter for the intake of thiamine (PubMed:10391222, PubMed:10542220, PubMed:21836059, PubMed:33008889, PubMed:35512554, PubMed:35724964). Mediates H(+)-dependent pyridoxine transport (PubMed:33008889, PubMed:35512554, PubMed:35724964)

Cell membrane

Thiamine-responsive megaloblastic anemia syndrome

An autosomal recessive disease characterized by megaloblastic anemia, diabetes mellitus, and sensorineural deafness. Onset is typically between infancy and adolescence, but all of the cardinal findings are often not present initially. The anemia, and sometimes the diabetes, improves with high doses of thiamine. Other more variable features include optic atrophy, congenital heart defects, short stature, and stroke.

Mediates high affinity thiamine uptake, probably via a proton anti-port mechanism (PubMed:11731220, PubMed:33008889, PubMed:35512554, PubMed:35724964). Has no folate transport activity (PubMed:11731220). Mediates H(+)-dependent pyridoxine transport (PubMed:33008889, PubMed:35512554, PubMed:35724964, PubMed:36456177)

Membrane

Basal ganglia disease, biotin-thiamine responsive

An autosomal recessive metabolic disorder characterized by episodic encephalopathy, often triggered by febrile illness, presenting as confusion, seizures, external ophthalmoplegia, dysphagia, and sometimes coma and death. If untreated, encephalopathies can result in permanent dystonia. Brain imaging may show characteristic bilateral lesions of the basal ganglia.

Antiporter that mediates the import of reduced folates or a subset of cyclic dinucleotides, driven by the export of organic anions (PubMed:10787414, PubMed:15337749, PubMed:16115875, PubMed:22554803, PubMed:31126740, PubMed:31511694, PubMed:32276275, PubMed:36071163, PubMed:36265513, PubMed:36575193, PubMed:7826387, PubMed:9041240). Acts as an importer of immunoreactive cyclic dinucleotides, such as cyclic GMP-AMP (2'-3'-cGAMP), an immune messenger produced in response to DNA virus in the cytoso

Cell membraneApical cell membraneBasolateral cell membrane

Megaloblastic anemia, folate-responsive

An autosomal recessive metabolic disorder characterized by megaloblastic anemia resulting from decreased folate transport into erythrocytes. Disease manifestations include hemolytic anemia, hyperhomocysteinemia, and low vitamin B12. Serum folate levels are normal, but erythrocyte folate levels are decreased. Treatment with oral folate corrects the anemia and normalizes homocysteine.

Copper metallochaperone essential for the synthesis and maturation of cytochrome c oxidase subunit II (MT-CO2/COX2); together with SCO1, facilitates the incorporation of copper into the Cu(A) site of MT-CO2/COX2 (PubMed:15229189, PubMed:17189203, PubMed:19336478, PubMed:35750769). Could also act as a thiol-disulfide oxidoreductase to regulate the redox state of the cysteines in SCO1 during maturation of MT-CO2/COX2 (PubMed:19336478)

Mitochondrion inner membrane

Mitochondrial complex IV deficiency, nuclear type 2

An autosomal recessive, severe mitochondrial disorder characterized by hypotonia, global developmental delay, hypertrophic cardiomyopathy, lactic acidosis, gliosis, and neuronal loss in basal ganglia, brainstem and spinal cord. Serum lactate is increased, and laboratory studies show decreased mitochondrial complex IV protein and activity levels in various tissues, including heart and skeletal muscle. Most patients die in infancy of cardiorespiratory failure.

Proton-coupled folate symporter that mediates folate absorption using an H(+) gradient as a driving force (PubMed:17129779, PubMed:17446347, PubMed:17475902, PubMed:19389703, PubMed:19762432, PubMed:25504888, PubMed:29344585, PubMed:30858177, PubMed:31494288, PubMed:31792273, PubMed:32893190, PubMed:34619546). Involved in the intestinal absorption of folates at the brush-border membrane of the proximal jejunum, and the transport from blood to cerebrospinal fluid across the choroid plexus (PubMed

Cell membraneApical cell membraneBasolateral cell membraneEndosome membraneCytoplasm

Hereditary folate malabsorption

Rare autosomal recessive disorder characterized by impaired intestinal folate absorption with folate deficiency resulting in anemia, hypoimmunoglobulinemia with recurrent infections, and recurrent or chronic diarrhea. In many patients, neurological abnormalities such as seizures or intellectual disability become apparent during early childhood, attributed to impaired transport of folates into the central nervous system. When diagnosed early, the disorder can be treated by administration of folate. If untreated, it can be fatal and, if treatment is delayed, the neurological defects can become permanent.

ATP-driven copper (Cu(+)) ion pump that plays an important role in intracellular copper ion homeostasis (PubMed:10419525, PubMed:11092760, PubMed:28389643). Within a catalytic cycle, acquires Cu(+) ion from donor protein on the cytoplasmic side of the membrane and delivers it to acceptor protein on the lumenal side. The transfer of Cu(+) ion across the membrane is coupled to ATP hydrolysis and is associated with a transient phosphorylation that shifts the pump conformation from inward-facing to

Golgi apparatus, trans-Golgi network membraneCell membraneMelanosome membraneEarly endosome membraneCell projection, axonCell projection, dendritePostsynaptic densityCytoplasm, cytosolEndoplasmic reticulum

Menkes disease

An X-linked recessive disorder of copper metabolism characterized by generalized copper deficiency. MNKD results in progressive neurodegeneration and connective-tissue disturbances: focal cerebral and cerebellar degeneration, early growth retardation, peculiar hair, hypopigmentation, cutis laxa, vascular complications and death in early childhood. The clinical features result from the dysfunction of several copper-dependent enzymes. A mild form of the disease has been described, in which cerebellar ataxia and moderate developmental delay predominate.

EGF stimulates the growth of various epidermal and epithelial tissues in vivo and in vitro and of some fibroblasts in cell culture. Magnesiotropic hormone that stimulates magnesium reabsorption in the renal distal convoluted tubule via engagement of EGFR and activation of the magnesium channel TRPM6. Can induce neurite outgrowth in motoneurons of the pond snail Lymnaea stagnalis in vitro (PubMed:10964941)

Membrane

Hypomagnesemia 4

A disorder characterized by massive renal hypomagnesemia and normal levels of serum calcium and calcium excretion. Clinical features include seizures, mild-to moderate psychomotor retardation, and brisk tendon reflexes.

Involved in regulation of the actin cytoskeleton. May regulate WAS actin-bundling activity. Bridges the interaction between ABL1 and PTPN18 leading to ABL1 dephosphorylation. May play a role as a scaffold protein between PTPN12 and WAS and allow PTPN12 to dephosphorylate WAS. Has the potential to physically couple CD2 and CD2AP to WAS. Acts downstream of CD2 and CD2AP to recruit WAS to the T-cell:APC contact site so as to promote the actin polymerization required for synapse induction during T-c

CytoplasmCell membraneCell projection, uropodiumCytoplasm, cytoskeletonCytoplasm, perinuclear regionCell projection, lamellipodiumCleavage furrow

Pyogenic sterile arthritis, pyoderma gangrenosum, and acne

A rare autosomal dominant autoinflammatory disease that typically presents with recurrent sterile, erosive arthritis in childhood, occurring spontaneously or after minor trauma, occasionally resulting in significant joint destruction. By puberty, joint symptoms tend to subside and cutaneous symptoms increase. Cutaneous manifestations include pathergy, frequently with abscesses at the sites of injections, severe cystic acne, and recurrent nonhealing sterile ulcers, often diagnosed as pyoderma gangrenosum.

Proton-coupled metal ion symporter operating with a proton to metal ion stoichiometry of 1:1 (PubMed:17109629, PubMed:17293870, PubMed:22736759, PubMed:25326704, PubMed:25491917). Selectively transports various divalent metal cations, in decreasing affinity: Cd(2+) > Fe(2+) > Co(2+), Mn(2+) >> Zn(2+), Ni(2+), VO(2+) (PubMed:17109629, PubMed:17293870, PubMed:22736759, PubMed:25326704, PubMed:25491917). Essential for maintenance of iron homeostasis by modulating intestinal absorption of dietary Fe

Early endosome membraneApical cell membraneLate endosome membraneLysosome membraneCell membraneExtracellular vesicle membraneMitochondrion outer membraneGolgi apparatus, trans-Golgi network membraneRecycling endosome membrane

Anemia, hypochromic microcytic, with iron overload 1

A hematologic disease characterized by abnormal hemoglobin content in the erythrocytes which are reduced in size. The disorder is due to an error of iron metabolism that results in high serum iron, massive hepatic iron deposition, and absence of sideroblasts and stainable bone marrow iron store. Despite adequate transferrin-iron complex, delivery of iron to the erythroid bone marrow is apparently insufficient for the demands of hemoglobin synthesis.

Liver-produced hormone that constitutes the main circulating regulator of iron absorption and distribution across tissues. Acts by promoting endocytosis and degradation of ferroportin/SLC40A1, leading to the retention of iron in iron-exporting cells and decreased flow of iron into plasma (PubMed:22682227, PubMed:29237594, PubMed:32814342). Controls the major flows of iron into plasma: absorption of dietary iron in the intestine, recycling of iron by macrophages, which phagocytose old erythrocyte

Secreted

Hemochromatosis 2B

A juvenile form of hemochromatosis, a disorder of iron metabolism with excess deposition of iron in a variety of organs leading to their failure, bronze skin pigmentation, hepatic cirrhosis, arthropathy and diabetes. The most common symptoms of juvenile hemochromatosis at presentation are hypogonadism and cardiomyopathy.