Mutant/mutation
The mutant lacks expression of Plasmodium BEM46-like protein (PBLP) and expresses GFP under the control of the constitutive promoter eef1a

Protein (function)
All eukaryotic organisms carry a homolog of the BEM46 protein,  which possesses a conserved amino acid motif in the a/ß-hydrolase superfamily  that includes enzymes with diverse functions and a wide range of substrates.  Although the biochemistry of these family members is well described,  few members of the a/ß-hydrolase superfamily have known biological functions  although BEM46 homologs have been implicated in playing a role in broad cellular  functions such as signal transduction and cell polarity in order to affect cell morphogenesis at the cell surface.
PBLP is conserved across Plasmodium spp., sharing structural homology and amino acid identity  with BEM46-like proteins in the a/ß-hydrolase super family. Like other BEM46 members,  the protein encodes a signal peptide that could act as a putative transmembrane domain at  the N-terminus and an a/ß-hydrolase domain at the C-terminus, the latter of which is common to  several hydrolytic enzymes with diverse catalytic functions. Additional BLAST searches in the P. yoelii 17XNL  genome revealed the presence of a number of additional putative BEM46 proteins,  none of which have been characterized to date.

Phenotype
While Δpblp blood stages initially grew at the same rate in mice as the WT parasites, there was a significant decrease in parasitemia levels throughout the course of infection, indicating that the mutants were unable to achieve the same level of growth as the WT parasites. The mutants smaller produced schizonts with visibly fewer merozoites when compared to WT parasites.
While there were no observable differences in exflagellation, Δpblp parasites produced approximately 30% fewer oocysts,  resulting in significantly fewer oocyst-derived sporozoites as compared to the WT.
Although there was also a decrease  in the number of salivary gland sporozoites of Δpblp as compared to the WT, it was roughly proportional  to the reduction of oocyst-derived sporozoite numbers. Evidence is presented that oocysts produced normal numbers of sporozoites. However, Δpblp sporozoites were visibly  thinner than WT sporozoites with altered CSP staining although the inner membrane complex (IMC) was unaffected  when assessed by myosin A-tail interacting protein (MTIP) staining. Additionally, Δpblp sporozoites displayed  altered intracellular staining patterns for BIP and TRAP, which implies that PBLP might have an additional role in sporozoite maturation.
Δpblp sporozoites show reduced host cell traversal and invasion in vitro and in vivo, resulting in a delay of prepatent period (1-2 days)  when mice are infected with sporozoites. Δpblp sporozoites are less motile than WT sporozoites.Δpblp parasites display a delay in liver stage development.

See also RMgm-110 for P. berghei mutant lacking expression of Plasmodium BEM46-like protein (PBLP)(PBANKA_071220). This mutant shows a different phenotype as the P. yoelii mutant described here. This P. berghei mutant showed strongly reduced sporozoite formation within oocysts. Sporozoites formed were not infectious to mice. In addition, it showed normal blood stage growth.

Additional information
Transcription in blood stages, sporozoites and liver stages.
Analysis of a mutant expressing a Cmyc-tagged version of PBLP (RMgm-1303) showed the following:
PBLP localizes to the parasite plasma membrane (PPM) in liver-stage and blood-stage parasites. In developing oocysts, PBLP significantly co-localized with the circumsporozoite protein (CSP) However, PBLP showed a unique intracellular localization in salivary gland derived pblp-myc tagged sporozoites,  which did not overlap with the ER marker BIP, the micronemal marker TRAP or the rhoptry marker  Ron4, although it was distinctly vesicular. In liver stgaes, at 24 hpi PBLP co-localized with CSP, which at this point is still  found associated with the parasite plasma membrane (PPM) of LS parasites. During later points of LS development,  PBLP co-localized with MSP-1 on the LS surface, clearly decorating the plasma membrane invaginations known  as cytomeres. In the final stage of exo-erythrocytic schizogony, PBLP continued to co-localize with MSP-1 on the  PPM of developed merozoites. Since PBLP was never shown to co-localize with the known parasitophorous vacuole membrane  (PVM) protein Hep17, these studies support that PBLP co-localizes with the PPM in blood and liver stages.

Other mutants
RMgm-110 - A P. berghei mutant lacking expression of Plasmodium BEM46-like protein (PBLP)(PBANKA_071220) (with a different phenotype as  the P. yoelii mutant described here).
A mutant expressing a Cmyc-tagged version of PBLP (RMgm-1303)