Fig. 1. Procedure for introducing mutations into the VSG 117 C-terminal GPI signal sequence. In the first PCR reaction, the mutation was introduced into VSG 117 with the wild-type and mutant primers P1 and P2. The second PCR reaction used the first PCR product (template 2) and a BspM I fragment (template 3) as templates. The forward primer in this reaction was P1 and the reverse primer P3. Because the final PCR product is a mixture of unmutated and mutated sequence, several plasmids were subjected to sequencing to identify the desired mutant derivative.