Mutant/mutation
The mutant lacks expression of both P52 and P36 and expresses RFP under control of the constitutive eef1α promoter The adjacent p52 and p36 genes have been deleted using a single DNA construct.

Protein (function)
P52 (P36) and P36 are members of a small family of proteins, the 6-cysteine (cys) family of (surface) proteins (Thompson J. et al., Mol. Biochem. Parasitol. (2001)118, 147-54). The proteins are characterised by domains of roughly 120 amino acids in size that contain six positionally conserved cysteines (6-cys). Although some species of Plasmodium (may) contain unique members of the 6-cys family, ten members have been identified that are conserved both in structure as well as in genome organisation throughout the genus. Some of the conserved 6-cys proteins are encoded by genes that form paralogous gene-pairs which are closely linked in the genome separated by less then 2 kb of intergenic region. Most members have a GPI anchor and are predicted membrane surface proteins whereas others appear to be secreted and most members are expressed in a discrete stage-specific manner in gametocytes, sporozoites or merozoites.
Both genes have been shown to play a role in invasion/development of sporozoites in hepatocytes (see PF3D7_0404400 and PF3D7_0404500.

Phenotype
Three knockout parasite lines were created: ΔP36, ΔP52 and ΔP52ΔP36.
None of the 17 mice injected with ΔP52 sporozoites became patent, and only 2 in 17 mice injected with the ΔP36 line became patent, the latter exhibited a patency delay of 1 day. In addition, only 2 in 45 mice injected with ΔP52ΔP36 parasites showed a blood infection, and patency in these animals was further delayed by an extra day.
In all 3 mutants no PVM was observed in infected Hepa 1–6 hepatoma cells. 

From the paper:  
'Here we show that parasites with a single P52 or P36 gene deletion each lack a PV after hepatocyte invasion, thereby pheno-copying the lack of a PV observed for the P52/P36 dual gene deletion parasite line. This indicates that both proteins are equally important in the establishment of a PV and act in the same pathway. We created a Plasmodium yoelii P36mCherry tagged parasite line that allowed us to visualize the subcellular localization of P36 and found that it partially co-localizes with P52 in the sporozoite secretory microneme organelles. Furthermore, through co-immunoprecipitation studies in vivo, we determined that P36 and P52 form a protein complex in sporozoites, indicating a concerted function for both proteins within the PV formation pathway. However, upon sporozoite stimulation, only P36 was released as a secreted protein while P52 was not. Our results support a model in which the putatively glycosylphosphatidylinositol (GPI)-anchored P52 may serve as a scaffold to facilitate the interaction of secreted P36 with the host cell during sporozoite invasion of hepatocytes.'

Additional information

Other mutants
see PF3D7_0404400 and PF3D7_0404500