CHARACTERIZATION OF O-LINKED GLYCOSYLATION MOTIFS IN THE GLYCOPEPTIDEDOMAIN OF BOVINE KAPPA-CASEIN

kappa-Casein is the major glycoprotein in bovine milk, It has a protei nase-sensitive (chymosin) site which cleaves the glycoprotein into two segments: N-terminal-para-kappa-casein domain and the C-terminal kapp a-casein macroglycopeptide domain which is highly heterogeneous in oli gosaccharide content, We have identified six sites of O-glycosylation on the macroglycopeptide by solid-phase Edman degradation: Thr121, Thr 131, Thr133, Thr136 (A variant only), Thr142 and Thr165. No Ser residu es are glycosylated, The glycosylation status of 15 of 17 potential O- glycosylation sites in the B variant was accurately predicted using th e four peptide moths previously proposed for the glycosylation of huma n glycophorin A (Pisano, A., Redmond, J. W., Williams, K. L. and Goole y, A. A., Glycobiology, 3, 429-435, 1993), provided one additional ass umption is made concerning an inhibitory role for a nearby Ile.