Probing polypeptide GalNAc-transferase isoform substrate specificities by in vitro analysis.
Glycobiology
; 25(1): 55-65, 2015 Jan.
Article
em En
| MEDLINE
| ID: mdl-25155433
ABSTRACT
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.
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Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Peptídeos
/
Polissacarídeos
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N-Acetilgalactosaminiltransferases
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article
País de afiliação:
Dinamarca