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MGP001147

UniProt Annotations

Entry Information
Gene NameUDP-galactose-4-epimerase
Protein EntryGALE_HUMAN
UniProt IDQ14376
SpeciesHuman
Comments
Comment typeDescription
Alternative ProductsEvent=Alternative splicing; Named isoforms=2; Name=1; IsoId=Q14376-1; Sequence=Displayed; Name=2; IsoId=Q14376-2; Sequence=VSP_056822; Note=No experimental confirmation available. {ECO:0000305};
Biophysicochemical PropertiesKinetic parameters: KM=69 uM for UDP-galactose (at 37 degrees Celsius and pH 8.8) {ECO:0000269|PubMed:11117433, ECO:0000269|PubMed:16302980}; Vmax=1.22 mmol/min/mg enzyme with UDP-galactose as substrate {ECO:0000269|PubMed:11117433, ECO:0000269|PubMed:16302980};
Catalytic ActivityUDP-alpha-D-glucose = UDP-alpha-D-galactose. {ECO:0000269|PubMed:22654673}.
Catalytic ActivityUDP-N-acetyl-alpha-D-glucosamine = UDP-N- acetyl-alpha-D-galactosamine. {ECO:0000269|PubMed:22654673}.
CofactorName=NAD(+); Xref=ChEBI:CHEBI:57540; Evidence={ECO:0000269|PubMed:10801319, ECO:0000269|PubMed:22654673, ECO:0000303|PubMed:11279032, ECO:0000303|PubMed:11279193};
DiseaseEpimerase-deficiency galactosemia (EDG) [MIM:230350]: Clinical features include early-onset cataracts, liver damage, deafness and mental retardation. There are two clinically distinct forms of EDG. (1) A benign, or 'peripheral' form with no detectable GALE activity in red blood cells and characterized by mild symptoms. Some patients may suffer no symptoms beyond raised levels of galactose-1-phosphate in the blood. (2) A much rarer 'generalized' form with undetectable levels of GALE activity in all tissues and resulting in severe features such as restricted growth and mental development. {ECO:0000269|PubMed:11903335, ECO:0000269|PubMed:16301867, ECO:0000269|PubMed:9326324, ECO:0000269|PubMed:9538513, ECO:0000269|PubMed:9973283}. Note=The disease is caused by mutations affecting the gene represented in this entry.
FunctionCatalyzes two distinct but analogous reactions: the reversible epimerization of UDP-glucose to UDP-galactose and the reversible epimerization of UDP-N-acetylglucosamine to UDP-N- acetylgalactosamine. The reaction with UDP-Gal plays a critical role in the Leloir pathway of galactose catabolism in which galactose is converted to the glycolytic intermediate glucose 6- phosphate. It contributes to the catabolism of dietary galactose and enables the endogenous biosynthesis of both UDP-Gal and UDP- GalNAc when exogenous sources are limited. Both UDP-sugar interconversions are important in the synthesis of glycoproteins and glycolipids. {ECO:0000269|PubMed:22654673, ECO:0000303|PubMed:23732289}.
MiscellaneousContrary to the human enzyme, the E.coli ortholog (AC P09147) does not catalyze the epimerization of UDP-N- acetylglucosamine to UDP-N-acetylgalactosamine. Compared to the E.coli enzyme, the sugar-binding pocket of the active site is 15% larger for the human enzyme, making it possible to accomodate the acetyl group. {ECO:0000269|PubMed:11279032}.
PathwayCarbohydrate metabolism; galactose metabolism.
Sequence CautionSequence=EAW95083.1; Type=Erroneous gene model prediction; Evidence={ECO:0000305}; Sequence=EAW95084.1; Type=Erroneous gene model prediction; Evidence={ECO:0000305}; Sequence=EAW95086.1; Type=Erroneous gene model prediction; Evidence={ECO:0000305}; Sequence=EAW95090.1; Type=Erroneous gene model prediction; Evidence={ECO:0000305}; Sequence=EAW95091.1; Type=Erroneous gene model prediction; Evidence={ECO:0000305}; Sequence=EAW95092.1; Type=Erroneous gene model prediction; Evidence={ECO:0000305}; Sequence=EAW95093.1; Type=Erroneous gene model prediction; Evidence={ECO:0000305};
SimilarityBelongs to the NAD(P)-dependent epimerase/dehydratase family. {ECO:0000305}.
SubunitHomodimer. {ECO:0000269|PubMed:10801319, ECO:0000269|PubMed:16302980}.
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