Cysteine protease which plays an essential role in merozoite egress from host erythrocytes (PubMed:22984267, PubMed:29459732). May cleave host SPTB/beta spectrin and ANK1/ankyrin-1 which disrupts host erythrocyte actin cytoskeleton and leads to host erythrocyte cell membrane rupture (PubMed:29459732). Expressed during parasite asexual blood stages, specifically at the schizont stage (at protein level). Just prior to merozoite egress from host erythrocytes, proteolytically cleaved by SUB1 to generate the active 75kDa form. Blood stage parasites are not viable (PubMed:29459732). Initial schizont development is normal but merozoite egress is abolished due to a failure to rupture the host erythrocyte membrane (PubMed:29459732). Does not affect poration of the host erythrocyte membrane which precedes erythrocyte membrane rupture (PubMed:29459732). Cleavage of host erythrocyte SPTB/beta spectrin and ANK1/ankyrin-1 is impaired (PubMed:29459732). Belongs to the peptidase C1 family.