MEMBRANE-BOUND CYSTEINE PROTEINASE ISOFORMS IN DIFFERENT DEVELOPMENTAL STAGES OF TRYPANOSOMA-CRUZI

Cysteine proteinase isoforms, immunologically cross-reactive with cruz ipain and with a similar apparent molecular mass, have been identified in epimastigotes of Trypanosoma cruzi by extraction and phase partiti on using the detergent Triton X-114. These isoforms are concentrated i n the microsomal fraction obtained after differential centrifugation, which is known to consist essentially of plasma membrane, can be label led by incubation of live parasites with sulfo-MIS-biotin, and bind to cystatin-sepharose affinity columns. They are present, albeit with a different electrophoretic pattern, in the epimastigote, amastigote and trypomastigote stages of the parasite.