Conservation of structure detected in two trypanosome surface glycoproteins by amino acid sequence alignment

The predominant molecule exposed to antibody on the surface of Trypanosoma brucei is a glycoprotein of about 60 000 molecular weight which varies in amino acid sequence. The complete sequences of two such variable surface glycoproteins (VSGs) from randomly isolated, different antigenic types of trypanosomes were compared by amino acid sequence alignment. Homologous sequences were found distributed over various regions of the VSGs. Particularly good homology was observed between residues 16-34, 91-115, 177-194 and 254-345 from the N-terminus, in addition to the known conserved region close to the C-terminus. Homology was also demonstrated in the corresponding regions of the cDNA sequences by matrix analysis.