Details

Autor(en) / Beteiligte

• Kong, Yun
• Joshi, Hiren J
• Schjoldager, Katrine Ter-Borch Gram
• Madsen, Thomas Daugbjerg
• Gerken, Thomas A
• Vester-Christensen, Malene B
• Wandall, Hans H
• Bennett, Eric Paul
• Levery, Steven B
• Vakhrushev, Sergey Y
• Clausen, Henrik

Titel

Probing polypeptide GalNAc-transferase isoform substrate specificities by in vitro analysis

Ist Teil von

• Glycobiology (Oxford), 2015-01, Vol.25 (1), p.55-65

Ort / Verlag

England: Oxford University Press

Erscheinungsjahr

2015

Quelle

Oxford Journals 2020 Medicine

Beschreibungen/Notizen

• N-acetylgalactosaminyltransferase (GalNAc)-type (mucin-type) O-glycosylation is an abundant and highly diverse modification of proteins. This type of O-glycosylation is initiated in the Golgi by a large family of up to 20 homologous polypeptide GalNAc-T isoenzymes that transfer GalNAc to Ser, Thr and possibly Tyr residues. These GalNAc residues are then further elongated by a large set of glycosyltransferases to build a variety of complex O-glycan structures. What determines O-glycan site occupancy is still poorly understood, although it is clear that the substrate specificities of individual isoenzymes and the repertoire of GalNAc-Ts in cells are key parameters. The GalNAc-T isoenzymes are differentially expressed in cells and tissues in principle allowing cells to produce unique O-glycoproteomes dependent on the specific subset of isoforms present. In vitro analysis of acceptor peptide substrate specificities using recombinant expressed GalNAc-Ts has been the method of choice for probing activities of individual isoforms, but these studies have been hampered by biological validation of actual O-glycosylation sites in proteins and number of substrate testable. Here, we present a systematic analysis of the activity of 10 human GalNAc-T isoenzymes with 195 peptide substrates covering known O-glycosylation sites and provide a comprehensive dataset for evaluating isoform-specific contributions to the O-glycoproteome.