Pattern of glycosylation of sindbis virus envelope proteins synthesized in hamster and chicken cells

Abstract

The tryptic glycopeptides of the Sindbis virus envelope glycoproteins El and E2 grown in BHK and chick cells were purified by gel filtration followed by high-pressure liquid chromatography. Each of the purified glycopeptides was analyzed by N-terminal sequencing to identify from which of the potential glycosylation sites it was derived. The type of oligosaccharide chain attached to each glycopeptide was determined from gel filtration analysis of the pronase-digested glycopeptides, and the relative incorporation of radiolabeled galactose, mannose, and glucosamine into each glycopeptide was used to confirm these determinations. The glycosylation patterns for the two proteins were essentialJy identical in the two host cells. The E2 glycosylation sites at Asn_(196) and Asn_(318) contained exclusively complex-type and simple-type oligosaccharide chains, respectively. In El, the glycosylation site at Asn_(139) contained only complex-type chains, but the site at Asn_(245) contained a mixture of simple (75-85%) and complex (15-25%) type chains. These results are discussed in relation to previously reported results and a prediction as to the relative importance of the different glycosylation sites to the function of the proteins is made.