Domain Annotation: SCOP2 Classification SCOP2 Database Homepage

ChainsTypeFamily Name Domain Identifier Family IdentifierProvenance Source (Version)
ASCOP2B SuperfamilySialyltransferase/TPK catalytic domain-like8053225 3000683 SCOP2B (2022-06-29)

Domain Annotation: ECOD Classification ECOD Database Homepage

ChainsFamily NameDomain Identifier ArchitecturePossible HomologyHomologyTopologyFamilyProvenance Source (Version)
APF00777e2wmlA1 A: a/b three-layered sandwichesX: Alpha-2,3/8-sialyltransferase CstII-related (From Topology)H: Alpha-2,3/8-sialyltransferase CstII-related (From Topology)T: Alpha-2,3/8-sialyltransferase CstII-relatedF: PF00777ECOD (1.6)

Domain Annotation: CATH CATH Database Homepage

ChainDomainClassArchitectureTopologyHomologyProvenance Source (Version)
A3.90.1480.20 Alpha Beta Alpha-Beta Complex sialyltransferase cstii, chain A Glycosyl transferase family 29CATH (4.3.0)

Protein Family Annotation Pfam Database Homepage

ChainsAccessionNameDescriptionCommentsSource
PF00777Glycosyltransferase family 29 (sialyltransferase) (Glyco_transf_29)Glycosyltransferase family 29 (sialyltransferase)- Family

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

ChainsPolymerMolecular FunctionBiological ProcessCellular Component
CMP-N-ACETYLNEURAMINATE-BETA-GALACTOSAMIDE -ALPHA-2\,3-SIALYLTRANSFERASE

InterPro: Protein Family Classification InterPro Database Homepage

Structure Motif Annotation: Mechanism and Catalytic Site Atlas M-CSA Database Homepage

ChainsEnzyme NameDescriptionCatalytic Residues
beta-galactoside alpha-2,3-sialyltransferase  M-CSA #340

Glycosyltransferase enzymes perform the sialyation of glycojonguates, molecules which have vital roles in cell recognition, adhesion and immunogenicity. The subset of sialyl-transferases (ST) catalyse the transfer of the sialic acid moiety from a cytidine-5'-monophosphate-N-acyl neuraminic acid donor to various acceptor glyco-conjuates terminating in either galactose, N-acetyl-galactosamine or another sialic acid. The enzyme annotated here, ST3Gal-I, catalyses the displacement reaction between CMP-N-acetylneuraminate and beta-D-Galactosyl-1,3-N-acetyl-alpha-D-galactosaminyl and is a member of the glycosyl transferase family 29. Bacterial sialytransferase enzymes contain a DXD domain which binds two divalent cations that are essential for catalysis. No such domain is present in the mammalian homologues, and the activity of these enzymes is found not to be dependent upon the presence of metal cofactors [PMID:19820709].

While the glycosyltransferase-catalysed reactions had been assumed to be uni-directional, the narrow difference in favourability for glycoside formation has been exploited to synthesise rare NDP-sugar products [PMID:16946071].

Defined by 2 residues: TYR:A-224 [auth A-269]HIS:A-274 [auth A-319]
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