Mutant/mutation
The mutant lacks expression of PIMMS43 and expresses mCherry under the constitutive hsp70 promoter

Protein (function)
PIMMS43 (Plasmodium Infection of the Mosquito Midgut Screen 43).
PIMMS43 encode deduced proteins of 505 and 350 amino acids, respectively. N-terminal signal peptides (amino acids 1 to 25 for PfPIMMS43 and 1 to 22 for PbPIMMS43) and C-terminal transmembrane domains (amino acids 482 to 504 for PfPIMMS43 and 327 to 350 for PbPIMMS43) are predicted for both proteins. The transmembrane domains are predicted by PredGPI to also contain signals for attachment of a GPI lipid anchor with 99% probability.

Our transcriptomic profiling of field P. falciparum isolates from Burkina Faso in the midgut of sympatric Anopheles coluzzii (previously Anopheles gambiae M form) and Anopheles arabiensis mosquitoes and a laboratory P. berghei strain in the midgut of A. coluzzii identified hundreds of genes exhibiting conserved and differential expression during gametocyte-to-oocyst development. Several of them encoding putatively secreted or membraneassociated proteins were made part of a screen to identify genes that function during parasite infection of the mosquito midgut. These genes were given a candidate gene number preceded by the acronym PIMMS, for “Plasmodium Infection of the Mosquito Midgut Screen.”
Here, we report the characterization of P. falciparum and P. berghei PIMMS43 that encodes a membrane-bound protein found on the surface of ookinetes and sporozoites. The gene was first reported in P. berghei to be a target of the transcription factor AP2-O, has a role in mosquito midgut invasion and oocyst development, and was named POS8. A later study by another group reported the gene as being important for ookinete maturation, designating it as PSOP25. Evidence is presented that PIMMS43 has no detectable function in ookinete maturation or mosquito midgut invasion but plays a key role in ookinete evasion of the mosquito complement-like response.

Phenotype
Normal blood stage development; normal production of gametocytes, gametes and ookinetes. In Anopheles coluzzi no oocyst formation; no sporozoite formation (in A stephensi low numbers of oocysts were observed, but no sporozoites).

Additional information
Evidence is presented that:
- PfPIMMS43 prominently localizes on the surface of female gametes or early stage zygotes found in the A. coluzzii blood bolus , as well as on the surface of ookinetes traversing the mosquito midgut epithelia and sporozoites found in the mosquito salivary gland lumen.
- Ookinetes Lacking PIMMS43 Are Killed by the Mosquito Complement-Like Response upon Midgut Traversal.
- PIMMS43 Is Additionally Required for Oocyst Maturation and Sporozoite Development
- PIMMS43 KO Leads to Compromised Ookinete Fitness and Attack by the Complement-Like Response
 
Other mutants