SUMMARY

aH-fucose and 14C-glucosamine labelled glycopeptides of the individual mem-brane proteins EI, E2 and E 3 of Semliki Forest virus could be sequentially digested with ~-neuraminidase, fl-galactosidase, N-acetyl-fl-glucosaminidase, ~- and fl-mannosidase, N-acetyl-fl-hexosaminidase nd finally with ~-fucosidase. The degradations of the virus glycopeptides proceeded in the same way as stepwise digestions of reference glycopeptides of the lactosamine type obtained from IgG and ~l-acid glycoprotein. This suggests that all three membrane glycoproteins of Semliki Forest virus contained glycans with a monosaccharide sequence charac-teristic for lactosamine type oligosaccharides. The number of both distal and proxi-mal N-acetyl-glucosamine residues was estimated to be usually two. According to exo- and endo-glycosidase digestions, fucose seemed to be attached to the innermost N-acetyl-glucosamine u it