1. Academic Validation
  2. Glycopeptide N-acetylgalactosaminyltransferase specificities for O-glycosylated sites on MUC5AC mucin motif peptides

Glycopeptide N-acetylgalactosaminyltransferase specificities for O-glycosylated sites on MUC5AC mucin motif peptides

  • Biochem J. 2001 Jul 1;357(Pt 1):313-20. doi: 10.1042/0264-6021:3570313.
D Tetaert 1 K G Ten Hagen C Richet A Boersma J Gagnon P Degand
Affiliations

Affiliation

  • 1 Unité INSERM No. 377, Biologie et Physiopathologie de Cellules Mucipares, Place de Verdun, 59045 Lille Cédex, France. tetaert@lille.inserm.fr
Abstract

The recombinant proteins of the two novel UDP-N-acetylgalactosamine (GalNAc) glycopeptide:N-acetylgalactosaminyltransferases (designated gpGaNTase-T7 and gpGaNTase-T9) were assayed with O-glycosylated products obtained from the prior action of the ubiquitous transferases (GaNTase-T1 and GaNTase-T2) towards MUC5AC Mucin motif Peptides (GTTPSPVPTTSTTSAP and Peptides with single amino acid substitutions, GTTPSAVPTTSTTSVP and GTTPSPVPTTSITSVP, that are a reflection of Mucin molecule polymorphism). gpGaNTase-T9 is known to be expressed differentially and more abundantly than gpGaNTase-T7 in some tissues; the results of in vitro glycosylation also indicates a difference in acceptor substrate specificities between the gpGaNTase isoforms. With the use of capillary electrophoresis, MS and Edman degradation, our study suggests that, in the O-glycosylation of mucin-type proteins, approach and recognition signalling by gpGaNTase-T7 and gpGaNTase-T9 depend largely on the peptide's primary structure (for example the presence of multiple clusters of hydroxy Amino acids and the number of GalNAc residues attached to the peptide backbone). O-glycosylation in terms of sites of attachment seems to be less random than previously described and, if sequential reactions are ordered throughout the Golgi stack, the complete O-glycosylation of the Mucin molecules seems to be finely tuned to respond to specific damage to, or attack on, epithelia.

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