Mutant/mutation
In the 'promoter-swap' mutant the RON5 promoter replaced by the promoter of PBANKA_1443300 (msp9). This promoter is active in asexual blood stages (in schizonts) but is silent in mosquito stages, such as oocysts and sporozoites. In addition the mutant expresses GFP under the constitutive eef1a promoter.

Protein (function)
RON5 is a rhoptry neck protein expressed in rhoptries of merozoites and sporozoites. RON5 is likely essential for blood stage growth and multiplication (like RON4 and RON2; see RMgm-2233). A number of rhoptry neck proteins (RONs), including RON2, RON4, and RON5 are secreted and inserted into the target cellular membrane as a complex. 

Phenotype
Sporozoite numbers from midguts and hemolymph were not significantly different from those of control parasites indicating that RON5 is not critical for sporozoite formation, maturation inside oocysts, and release to the hemocoel. In contrast, the mean numbers of sporozoites residing in salivary glands were reduced 41-fold. Sporozoites showed reduced adhesion and gliding motility.

38% of control wild type hemolymph sporozoites start gliding, while 55% remain floating without attachment to the glass slide.  In contrast, approximately 85% of RON5-cKD hemolymph sporozoites drifted. These results indicate that RON5 is required for hemolymph sporozoite attachment to the glass slide. Accordingly, only 5% of RON5-cKD hemolymph sporozoites show gliding, which is 7-fold less than wild type gliding sporozoites, 

Additional information
From the Abstract of the paper:
'Components of the merozoite rhoptry neck protein complex are also expressed in sporozoites, namely, RON2, RON4, and RON5, suggesting that invasion mechanism elements might be conserved between these infective stages. Recently, we demonstrated that RON2 is required for sporozoite invasion of mosquito salivary gland cells and mammalian hepatocytes, using a sporozoite stage-specific gene knockdown strategy in the rodent malaria parasite model, Plasmodium berghei. Here, we use a coimmunoprecipitation assay and oocyst-derived sporozoite extracts to demonstrate that RON2, RON4, and RON5 also form a complex in sporozoites. The sporozoite stage-specific gene knockdown strategy revealed that both RON4 and RON5 have crucial roles during sporozoite invasion of salivary glands, including a significantly reduced attachment ability required for the onset of gliding. Further analyses indicated that RON2 and RON4 reciprocally affect trafficking to rhoptries in developing sporozoites, while RON5 is independently transported.'

Other mutants