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Search The CSA
PDB ID
UNIPROT ID
EC Number

Catalytic Site Atlas

CSA LITERATURE entry for 1kws

E.C. namegalactosylgalactosylxylosylprotein 3-beta-glucuronosyltransferase
SpeciesHomo sapiens (Human)
E.C. Number (IntEnz) 2.4.1.135
CSA Homologues of 1kws1fgg,1v82,1v83,1v84,2d0j,3cu0,
CSA Entries With UniProtID O94766
CSA Entries With EC Number 2.4.1.135
PDBe Entry 1kws
PDBSum Entry 1kws
MACiE Entry 1kws

Literature Report

IntroductionBeta-1,3-glucuronyltransferase (GlcAT-I) is involved in the biosynthesis of heparin sulphate and chondroitin sulphate. It catalyses the transfer of glucuronic acid (GlcUA) from UDP-GlcUA onto the terminal galactose of the linker Gal-Gal-Xyl- that is attached to a serine side chain of a core protein. GlcAT-I is an inverting glycosyltransferse, converting the alpha linkage in the UDP-GlcUA molecule to a beta linkage in the product.
MechansimThe reaction is thought to proceed via an oxo-carbenium ion-like transition state. Accumulation of negative charge on the departing pyrophosphate moiety of the UDP leaving group is stabilised by a divalent metal ion, while the attacking C3 OH of the terminal galactose is deprotonated by Glu 281.
Reaction

Catalytic Sites for 1kws

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
GluA281281macie:sideChainDeprotonates the C3 hydroxyl of the terminal galactose moiety that attacks C1 of the UDP-GlcUA molecule.

Annotated By Reference To The Literature - Site 2 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
GluB281281macie:sideChainDeprotonates the C3 hydroxyl of the terminal galactose moiety that attacks C1 of the UDP-GlcUA molecule.

Literature References

Notes:
Pedersen LC
Crystal structure of beta 1,3-glucuronyltransferase I in complex with active donor substrate UDP-GlcUA.
J Biol Chem 2002 277 21869-21873
PubMed: 11950836
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