Trypanosoma brucei brucei, T. brucei gambiense, and T. brucei rhodesiense: common glycoproteins and glycoprotein oligosaccharide heterogeneity identified by lectin affinity blotting and endoglycosidase H treatment.

Whole cell extracts of 10 clones of bloodstream forms of African trypanosomes representing two strains of Trypanosoma brucei gambiense, one strain of T. b. rhodesiense and one strain of T. b. brucei were fractionated on sodium dodecyl sulfate-polyacrylamide gels, electrophoretically transferred to nitrocellulose paper, and probed with horseradish peroxidase conjugated lectins to detect glycoproteins. Variant specific glycoproteins of all 10 clones bound peroxidase labeled concanavalin A, but peroxidase labeled wheat germ agglutinin bound to the variant specific glycoproteins of only 3 of the 10 clones examined. In addition, 22 other glycoproteins expressed in common by all clones bound peroxidase labeled concanavalin A; 19 common glycoproteins bound peroxidase labeled wheat germ agglutinin. Lectin binding to transferred glycoproteins was specifically inhibited by appropriate monosaccharides, alpha-methyl mannoside for concanavalin A and N-acetyl glucosamine for wheat germ agglutinin. Prior incubation of blots in endo-beta-N-acetylglucosaminidase H eliminated binding of peroxidase-labeled concanavalin A to most of the 22 common glycoproteins. Two glycoproteins, designated Gp 81 and Gp 110, were the major Endoglycosidase H resistant components. Endoglycosidase H treatment also reduced binding of peroxidase labeled concanavalin A to the variant specific glycoproteins of 7 clones. The variant specific glycoproteins from the 3 clones that bound peroxidase labeled concanavalin A following enzyme treatment were those that bound peroxidase labeled wheat germ agglutinin. These results show that African trypanosomes express a greater number of glycoproteins than has been reported previously and that only a limited number of these glycoproteins bear Endoglycosidase H resistant oligosaccharides.