Mutant/mutation
The mutant lacks expression of a (plant like) calcium-dependent protein kinase 4 (CDPK4).

Protein (function)
CDPK4 belongs to an expanded family of Ca²⁺ dependent protein kinases (CDPKs). CDPKs combine an amino-terminal serine/threonine kinase domain and a carboxy-terminal calmodulin-like domain, composed of four EF hands, in the same molecule. In plants, CDPKs translate Ca²⁺ signals generated by external stimuli into cellular responses, thereby regulating cell division and differentiation, the development of tolerance to stress stimuli and the specific defense responses to pathogens.

Phenotype
The phenotype of the male gametocytes/gametes indicate that CDPK4 controls S-phase entry in the male gametocyte. In the mutant DNA replication in the male gametocytes to form the 8 motile gametes is blocked.
The reduced infectivity of ookinetes, resulting from crossing mutant female gametes with wildtype male gametes suggests a second function of CDPK4 later during sporogonic development.

Additional information
Disruption of the P. falciparum ortholog has been succesful (Solyakov et al., 2011, Nat Commun, 2:565) indicating that this gene is not essential for asexual proliferation.
 

Other mutants
RMgm-154: A mutant lacking expression of CDPK3
RMgm-165: A mutant lacking expression of CDPK3
RMgm-168: A mutant lacking expression of CDPK3 and expressing GFP under control of the hsp70 promoter. This mutant has been generated by crossing mutant RMgm-165 lacking expression of CDPK3 with mutant RMgm-166 that expresses GFP.