Mutant/mutation
The mutant lacks expression of PIMMS2 and expresses GFP under the constitutive eef1a promoter.

Protein (function)
PBANKA_1106900, is mapped between genes encoding two known subtilisin-like proteases, SUB1 and SUB3, and encodes an 836 amino acid long protein. Bioinformatics analysis predicted with high probability two hydrophobic regions of alpha helix structure encompassing the amino acid residues 6-25 and 416-427, respectively. Additionally,  a cleavage site at amino acid residue 30 was predicted suggesting an N-terminal signal peptide and a transmembrane domain located at the center of the protein. Protein sequence analysis predicted a peptidase S8 domain (IPR000209) that ends shortly after the predicted transmembrane domain and is followed by a long C-terminal extension (CTE)  with no known domain homology. A highly significant (100% confidence) structural similarity was predicted of the predicted peptidase S8 domain region to the P. vivax SUB1, and P. falciparum SUB1. PIMMS2 sequence alignments with PvSUB1 and the bacterial subtilisin BPN’ identified several conserved amino acid residues within the predicted subtilisin-like domain including D155, H122 and S414, which correspond to the catalytic triad of subtilisin-like serine proteases. A conserved asparagine residue N328 that serves in stabilizing the putative oxyanion hole was also identified. However, the conserved motifs HGT and GTS, which encompass the catalytic His and Ser residues of subtilases, respectively, are not present in PIMMS2, suggesting that the putative catalytic triad is likely to be non-functional and thus PIMMS2 is a potential pseudoenzyme.
The subtilisin-like domain architecture of PbPIMMS2 is conserved only in PvPIMMS2; the  rest of the PIMMS2 orthologs appear to lack one or more of the conserved amino acid residues or motifs.

Phenotype
Normal ookinete production. Normal ookinete motility. Significantly reduced oocyst numbers/production.Significantly reduced salivary gland numbers/production. Sporozoites were infective to mice as shown by bite-back experiments.
Evidence is presented that ookinetes fail to traverse the midgut epithelium (see below)

Additional information
PIMMS2 transcripts are limited to mosquito midgut stages. Transcripts were as early as 1 h post gametocyte activation and peaked as the ookinete development progressed. No PIMMS2 transcripts were detected in the oocyst.
Immunofluorescence assays revealed a prominent surface distribution of PIMMS2 in in vitro produced ookinetes that were permeabilized using Triton. This signal was largely abolished in non-permeabilized ookinetes suggesting that the subtilisin-like domain of PIMMS2, against which the antibody was raised, is located on the internal side of the ookinete surface. The surface distribution of P28, which was used as a control, showed no difference between permeabilized and non-permeabilized ookinetes, and it was not affected by the disruption of PIMMS2.

From the paper 'Next, we examined whether the Δpbpimms2 ookinetes fail to traverse the mosquito midgut epithelium or are eliminated after they traverse the epithelium, prior to their development to oocysts. Infections with Δpbpimms2 and c507 control parasites were carried out in A. gambiae L3-5 mosquitoes that are known to melanize P. berghei ookinetes immediately after they traverse the epithelium, upon exiting into the basal sub-epithelial space. Therefore, this assay provides a powerful means of quantifying the ookinete invasive ability. To control for variation in gametocyte numbers, membrane feeds of equal numbers of in vitro cultured ookinetes were performed. The results revealed that there were significantly lower numbers of melanized Δpbpimms2 ookinetes compared to c507 controls, indicating that the Δpbpimms2 phenotype is due to the failure of mutant ookinetes to traverse the midgut epithelium'.

Other mutants
 RMgm-4174 - a mutant expressing a mutated form of PIMMS2 (the conserved Asp155, His222 and Ser414 residues of PIMMS2, which make up the catalytic triad of subtilases, were replaced with alanine residues by site-directed mutagenesis).