Influence of β-adrenergic stimulation on glycosylation of a major, secretory N-linked glycoprotein from rat parotid salivary gland

Abstract

β-Adrenergic stimulation with 10 μM isoproterenol increased the [ 3H]-mannose/[ 14C]-leucine ratio (three- to six-fold) of protein extracts in double-radiolabelled rat parotid acinar cells. Characteristics of oligosaccharides in a major parotid glycoprotein ( M r ~ 220,000; gp 220) were studied. Gp 220 from control and experimental cells was endoglycosidase H-insensitive, endoglycosidase F-sensitive and bound both concanavalin A and wheat germ agglutinin. Gp 220 was removed from concanavalin A-Sepharose by sequential elution with 10mM α-methyl glucoside and 0.5 M α-methyl mannoside. These findings suggest that (1) oligosaccharides in gp 220 have both a biantennary complex and hybrid oligosaccharide chains, and (2) β-adrenoreceptor stimulation has little effect on the gross oligosaccharide structures of this glycoprotein.