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- Title
Characterization of ppGalNAc-T18, a member of the vertebrate-specific Y subfamily of UDP-N-acetyl-α-d-galactosamine:polypeptide N-acetylgalactosaminyltransferases †.
- Authors
Li, Xing; Wang, Jing; Li, Wei; Xu, Yingjiao; Shao, Dong; Xie, Yinyin; Xie, Wenxian; Kubota, Tomomi; Narimatsu, Hisashi; Zhang, Yan
- Abstract
The first step of mucin-type O-glycosylation is catalyzed by members of the UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (ppGalNAc-T; EC 2.4.1.41) family. Each member of this family has unique substrate specificity and expression profiles. In this report, we describe a new subfamily of ppGalNAc-Ts, designated the Y subfamily. The Y subfamily consists of four members, ppGalNAc-T8, -T9, -T17 and -T18, in which the conserved YDX5WGGENXE sequence in the Gal/GalNAc-T motif of ppGalNAc-Ts is mutated to LDX5YGGENXE. Phylogenetic analysis revealed that the Y subfamily members only exist in vertebrates. All four Y subfamily members lack in vitro GalNAc-transferase activity toward classical substrates possibly because of the UDP-GalNAc-binding pocket mutants. However, ppGalNAc-T18, the newly identified defining member, was localized in the endoplasmic reticulum rather than the Golgi apparatus in lung carcinoma cells. The knockdown of ppGalNAc-T18 altered cell morphology, proliferation potential and changed cell O-glycosylation. ppGalNAc-T18 can also modulate the in vitro GalNAc-transferase activity of ppGalNAc-T2 and -T10, suggesting that it may be a chaperone-like protein. These findings suggest that the new Y subfamily of ppGalNAc-Ts plays an important role in protein glycosylation; characterizing their functions will provide new insight into the role of ppGalNAc-Ts.
- Subjects
N-acetylgalactosaminyltransferase genetics; GALACTOSAMINE; POLYPEPTIDES; GLYCOSYLATION; PHYLOGENY; ENDOPLASMIC reticulum; GOLGI apparatus
- Publication
Glycobiology, 2012, Vol 22, Issue 5, p602
- ISSN
0959-6658
- Publication type
Article
- DOI
10.1093/glycob/cwr179