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Crystal structure of GalNAc-T7 with UDP, GalNAc and Mn2+
Structural highlights
FunctionGALT7_HUMAN Glycopeptide transferase involved in O-linked oligosaccharide biosynthesis, which catalyzes the transfer of an N-acetyl-D-galactosamine residue to an already glycosylated peptide. In contrast to other proteins of the family, it does not act as a peptide transferase that transfers GalNAc onto serine or threonine residue on the protein receptor, but instead requires the prior addition of a GalNAc on a peptide before adding additional GalNAc moieties. Some peptide transferase activity is however not excluded, considering that its appropriate peptide substrate may remain unidentified. Publication Abstract from PubMedThe UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts) catalyze mucin-type O-glycosylation by transferring alpha-N-acetylgalactosamine (GalNAc) from UDP- GalNAc to Ser or Thr residues of target proteins. We resolved the crystal structures of GalNAc-T7, a GalNAc-T capable of glycosylating consecutive sites, and of its complex with the donor substrate UDP-GalNAc. The N-terminal catalytic domain and C-terminal lectin domain are connected by a flexible linker, forming a narrow cleft for the acceptor substrate. Only the alpha subdomain of the lectin domain binds to the glycosyl group, indicating that key residues determine substrate binding. Compared to the Apo structure, the loop covering the catalytic center of the complex show significant conformational changes, indicating the mechanism of the catalytic reaction. Structural basis of carbohydrate transfer activity of UDP-GalNAc: Polypeptide N-acetylgalactosaminyltransferase 7.,Yu C, Liang L, Yin Y Biochem Biophys Res Commun. 2019 Mar 5;510(2):266-271. doi:, 10.1016/j.bbrc.2019.01.084. Epub 2019 Jan 23. PMID:30685086[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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