Mutant/mutation
The mutant expresses a HA-tagged version of SUB1

Protein (function)
The subtilisin-like protease SUB1, a bacterial-like serine protease, is a Plasmodium merozoite product essential for the parasite erythocytic cycle. In P. falciparum, SUB1 was shown to have a dual function. It is crucial for merozoite egress from erythrocytes and renders released merozoites competent for a new round of erythrocyte invasion. In the process of P. falciparum merozoite egress from erythrocytes, SUB1 carries out the maturation of the family of papain-like proteases called serine repeat antigens (SERAs). It remains unknown whether the SERAs have a direct role in membrane disruption, or whether they in turn maturate other effectors, but it is established that their SUB1-dependent maturation is essential for the egress of merozoite. The reported role of SUB1 in P. falciparum merozoite invasion is to undertake the processing of merozoite surface proteins (MSPs), including MSP1. After SUB1 maturation, the membrane-anchored C-terminal 42-kDa fragment of MSP1, remains associated with the other MSP1 fragments and additional partners, including MSP6 and MSP7. Analyses of conditional knock-out mutants lacking expression of SUB1 in liver stages (RMgm-952, RMgm-972) show an essential role of SUB1 for formation of infectious merozoites

Phenotype
PbSUB1-HA expression in blood and liver stages. No expression in sporozoites or early liver stages.
PbSUB1-HA schizonts with the anti-HA mAb again produced a clear punctate signal. The foci were associated with but distinct from individual merozoite nuclei, and similar to the exoneme-specific signal previously observed in P. falciparum blood stage schizonts.

Additional information

Other mutants
RMgm-952: An independent mutant containing a FRTed ORF of the sub1 locus
RMgm-972: An independent mutant containing a FRTed ORF of the sub1 locus