Mutant/mutation
The mutant lacks expression of the P48/45 protein and expresses GFP under the control of a male specific promoter and RFP under the control of a female specific promoter.

Protein (function)
The P48/45 protein (PF13_0247) is a member 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 characterized 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 organization throughout the genus (Thompson et al., 2001). 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.
P48/45 is a surface protein of both male and female gametes and is considered as a major candidate antigen for development of a transmission blocking vaccine.

Phenotype
Phenotype analyses demonstrate that P48/45 plays an important role in fertilization (male fertility factor). Motile males fail to attach to and penetrate female gametes (see phenotype description). Mutant female gametes are fertile as has been shown by cross-fertilisation with wild type male gametes.

This mutant shows the same phenotype as mutant RMgm-15 which has been characterized in more detail. This mutant has been generated to be able to distinguish the female gametocytes/gametes and ookinetes based on their RFP expression in cross-fertilisation experiments with fertile males of other mutants (see below) and for determination of meiosis in cross-fertilisation studies. Meiosis in zygotes is determined by FACS analysis of the DNA content of Hoechst-stained gametes/zygotes selected based on their RFP-fluorescence.

Mutants lacking expression of P48/45 are frequently used in cross-fertilization studies in which the fertile females are used to test the fertility of males of other mutants (Khan et al., Cell (2005) 121, 675-87; Raine, J.D. et al., PLoS Pathog (2007) 3,e30; Ponzi et al, 2009, Cell Microbiol. 11, 1272-88).
These mutants  show very low levels of fertilization with higher fertilization rates in the mosquito than in in vitro ookinete cultures. Mutant parasites produce low numbers of ookinetes and oocysts in Anopheles stephensi mosquitoes (see also the phenotype description 'Fertilization and ookinete'). Both the ookinetes and oocysts show a normal morphology and oocysts produce normal numbers of sporozoites that are infectious to mice.

Additional information

Table: P. falciparum gene members of the 6-cys family

Other mutants
RMgm-15: An independent mutant lacking expression of P48/45
RMgm-349: A mutant lacking expression of both P47 and P48/45
RMgm-346: An independent mutant lacking expression of P48/45 which expresses GFP under the constitutive eef1a promoter. This mutant shows the same phenotype as other mutants lacking expression of P48/45. This mutant has been generated to be able to distinguish the female gametocytes and ookinetes based on their high GFP expression in cross-fertilisation experiments with fertile males of other mutants.