Characterization of O-linked glycosylation motifs in the glycopeptide domain of bovine kappa-casein.
kappa-Casein is the major glycoprotein in bovine milk. It has a proteinase-sensitive (chymosin) site which cleaves the glycoprotein into two segments: N-terminal para-kappa-casein domain and the C-terminal kappa-casein macroglycopeptide domain which is highly heterogeneous in oligosaccharide content. We have identified six sites of O-glycosylation on the macroglycopeptide by solid-phase Edman degradation: Thr121, Thr131, Thr133, Thr136 (A variant only), Thr142 and Thr165. No Ser residues are glycosylated. The glycosylation status of 15 of 17 potential O-glycosylation sites in the B variant was accurately predicted using the four peptide motifis previously proposed for the glycosylation of human glycophorin A (Pisano, A., Redmond, J.W., Williams, K.L. and Gooley, A.A., Glycobiology, 3, 429-435, 1993), provided one additional assumption is made concerning an inhibitory role for a nearby Ile.
Pisano
A
A
Macquarie University Centre for Analytical Biotechnology (MUCAB), Macquarie University, Sydney, NSW, Australia.
Packer
N H
NH
Redmond
J W
JW
Williams
K L
KL
Gooley
A A
AA
D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins / Q000737:chemistry* / Q000235:genetics; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D006020:Glycopeptides / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D006031:Glycosylation; D006801:Humans; D007532:Isoleucine / Q000737:chemistry; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
D002364:Caseins; D006020:Glycopeptides; D007532:Isoleucine