The biosynthesis of Trypanosoma brucei variant surface glycoproteins--in vitro processing of signal peptide and glycosylation using heterologous rough endoplasmic reticulum vesicles.

The ability of stripped microsomal dog pancreas vesicles to process precursors of the variant glycoprotein of Trypanosoma brucei has been investigated. The vesicles were shown to be capable of cleaving a peptide precursor variant surface glycoprotein, identified as the N-terminal signal peptide in the case of one variant. The vesicles were also shown to add carbohydrate to precursor variant surface glycoprotein. This carbohydrate, which was sensitive to the action of endo-H was located within a C-terminal CNBr fragment in one variant. However, the vesicles were not capable of adding the oligosaccharide carrying the variant surface glycoprotein cross-reacting determinant.