alpha-1,3-galactosyltransferase 2; isoglobotriaosylceramide synthase; iGb3 synthase; iGb3S (A3GALT2, A3GALT2P, IGBS3S)

Function: - synthesizes galactose-alpha(1,3)-galactose group on the glycosphingolipid isoglobotrihexosylceramide or isogloboside 3 (iGb3) by catalyzing transfer of galactose from UDP-galactose to its acceptor molecule gal-beta-1,4-Glc-ceramide - can also catalyze the addition of galactose to iGb3 itself to form polygalactose structures UDP-alpha-D-galactose + beta-D-galactosyl-(1->4)-beta-N-acetyl-D-glucosaminyl-R = UDP + alpha-D-galactosyl-(1->3)-beta-D-galactosyl-(1->4)-beta-N-acetylglucosaminyl-R Cofactor: Mn+2 Structure: - conserved DXD motif is involved in cofactor binding - the Mn+2 interacts with the beta-phosphate group of UDP & may also have a role in catalysis (putative) - belongs to the glycosyltransferase 6 family Compartment: G - Golgi apparatus, Golgi stack membrane - also found in numerous large vesicles throughout the cytoplasm of the soma - single-pass type II membrane protein Expression: - expressed in thymus & monocyte derived dendritic cells Note: - the spliced A3GALT2 mRNA may not be detected in human tissues - functional activity of human A3GALT2 tested by expressing a chimeric protein containing the catalytic domain of human A3GALT2 is unable to synthesize isogloboside 3 (iGb3) - in rat, mutant 'Asn-253' of human A3GALT2 completely eliminates alpha-1,3-galactosyltransferase activity

General

galactosyltransferase glycoprotein membrane protein

Properties

SIZE: entity length = 340 aa MW = 39 kD COMPARTMENT: cytoplasm golgi MOTIF: transmembrane domain {13-32} N-glycosylation site {N58} N-glycosylation site {N100} manganese [Mn]-binding site SITE: 199-199 manganese [Mn]-binding site SITE: 201-201

Database Correlations

UniProt U3KPV4 Pfam PF03414 Entrez Gene 127550 Kegg hsa:127550 ENZYME 2.4.1.87

References

UniProt :accession U3KPV4