Sites of asparagine-linked oligosaccharides in porcine 32 kDa enamelin.
The 32 kDa enamelin protein isolated from developing porcine enamel was previously shown to contain eight different asparagine-linked oligosaccharides. However, only three consensus attachment sites were evident in this protein. In this study, glycopeptides containing all three potential glycosylation sites (72-Asn, 79-Asn and 91-Asn) were purified from 32 kDa enamelin. The oligosaccharides were isolated from each glycopeptide following digestion with N-oligosaccharide glycopeptidase, labeled with 2-aminopyridine at the reducing ends, and then characterized by reverse phase HPLC. All three potential sites were found to be glycosylated heterogeneously (i.e., five biantennary complexes at 72-Asn, two biantennary complexes at 79-Asn, three triantennary complexes at 91-Asn), accounting for all eight oligosaccharides characterized previously. These results indicate that 32 kDa enamelin has a complex pattern of asparagine-linked glycosylation localized within a small region (20 residues) of the protein. The functional significance of this glycosylation remains to be established.
Yamakoshi
Y
Y
Department of Biochemistry, School of Dental Medicine, Tsurumi University, Yokohama, Japan.
Pinheiro
F H
FH
Tanabe
T
T
Fukae
M
M
Shimizu
M
M
D000818:Animals; D001216:Asparagine; D003746:Dental Enamel Proteins / Q000032:analysis*; D006020:Glycopeptides / Q000032:analysis*; D009844:Oligosaccharides / Q000032:analysis*; D011402:Pronase; D012697:Serine Endopeptidases; D013552:Swine
D003746:Dental Enamel Proteins; D006020:Glycopeptides; D009844:Oligosaccharides; C038456:tuftelin; D001216:Asparagine; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D011402:Pronase