Structure and glycosylation of tacaribe viral glycoproteins

The virion glycoprotein (G) of Tacaribe virus was separated into multiple components by two-dimensional electrophoresis. The most acidic glycoprotein species, which migrated most rapidly toward the anode, were found to differ from less acidic species primarily in their sialic acid content. A previously undetected basic component yielded a peptide map dissimilar to the map of the acidic component; however, after neuraminidase digestion, peptide maps of the basic and acidic component were very similar. We have detected at least two glycopeptide size classes by analysis of Pronase digests of Tacaribe G protein as well as a precursor designated gp70. The larger size class (～ 3300 daltons) was labeled with glucosamine, galactose, or mannose and appeared to contain neuraminic acid as indicated by sensitivity to neuraminidase. The smaller size class (1600–1900 daltons) contained a high amount of mannose in addition to glucosamine and was sensitive to endo-β-N-acetylglucosaminidase H. The G glycoprotein was composed mainly of large glycopeptides, whereas the gp70 glycoprotein contained mostly the smaller mannose-rich glycopeptides.