RESTORATION OF LECTIN ACTIVITY TO A NONGLYCOSYLATED RICIN B-CHAIN MUTANT BY THE INTRODUCTION OF A NOVEL N-GLYCOSYLATION SITE

Ricin B chain (RTB) is an N-glycosylated, galactose-specific lectin, R emoval of the two native N-glycosylation sites at Asn(95) and Asn(135) by site-directed mutagenesis generated a recombinant protein devoid o f lectin activity, Two novel N-glycosylation sites were introduced int o RTB at Asn(42) and Asn(123), either singly or in combination, Microi njection of pre-RTB transcripts into Xenopus oocytes showed that these novel sites became glycosylated in vivo, The single oligosaccharide s ite chain at Asn(42) restored lectin activity to RTB, whereas glycosyl ation at Asn(123) or simultaneous glycosylation at Asn(42) and Asn(123 ) failed to do so. (C) 1997 Federation of European Biochemical Societi es.