9. Which of the following amino acid can have o-glycoxylation linkage in oligosachride molecule

         A.Asparagine

        B. glutamine

        C. serine

         D. cysteine

Ans Serine

THERE ARE THREE MAJOR CLASSES OF GLYCOPROTEINS

Based on the nature of the linkage between their polypeptide chains and their oligosaccharide chains, glycoproteins

can be divided into three major classes (Figure 47–1): (1) those containing an O-glycosidic linkage (ie, Olinked),

involving the hydroxyl side chain of serine or threonine and a sugar such as N -acetylgalactosamine

(GalNAc-Ser[Thr]); (2) those containing an N-glycosidic linkage (ie, N-linked), involving the amide nitrogen of

asparagine and N -acetylglucosamine (GlcNAc-Asn); and (3) those linked to the carboxyl terminal amino acid of a

protein via a phosphoryl-ethanolamine moiety joined to an oligosaccharide (glycan), which in turn is linked via

glucosamine to phosphatidylinositol (PI). This latter class is referred to as glycosylphosphatidylinositolanchored

(GPI-anchored, or GPI-linked ) glycoproteins