Mutant/mutation
In the mutant the open reading frame of actin II is replaced by a mutated form of act I. The mutant thus contains two actin I genes, the endogenous gene under the contol of its own 5' and 3'UTRs and one under the control of the 5' and 3'UTRs of the actin II gene. The mutated actin I is a  chimera, where residues 40–61 of  P. berghei actin I were replaced by the corresponding residues from a-actin of pig skeletal muscle, and two point mutations (G115A and F54Y) were introduced to actin I, thereby exchanging the D-loop of P. berghei actin I to that of a-actin (i.e. the canonical D-loop)

Protein (function)
Actin, a cytoskeletal protein, has many diverse functions in eukaryotic cells ranging from roles in cell motility, cell division, vesicle trafficking to functions in cell signaling and regulation of transcription. A critical property of actin is its ability to form filamentous polymers (F-actin), and a plethora of proteins are involved in the highly dynamic regulation of F-actin formation . Actins are highly conserved proteins that often exist in multiple isoforms in the eukaryotic cell and their expression is regulated both spatially and temporally during development. The number of conventional actin genes varies among eukaryotic organisms. A few single cell eukaryotes, such as Saccharomyces cerevisiae, Toxoplasma gondii, and Trypanosoma brucei encode a single actin gene, which results in lethality when targeted with gene ablation approaches. Many organisms, however, have several conventional actin genes.Apicomplexan parasites all encode one major actin isoform, here termed Actin I. All apicomplexan parasites also contain a number of actin-related and actin-like proteins. Plasmodium species species stand out in that they all encode a second conventional actin, termed Actin II.

Phenotype analyses of mutants lacking the actin II gene (RMgm-632) indicate that Actin II plays a major role during the formation of the male gametes (no exflagellation of male gametocytes; no male gamete formation). Female gametes are fertile as shown in cross-fertilisation studies with fertile male gametes.

Mutants in which the actin II is replaced by mutant 1 (act2rep; RMgm-935) show a partly restored exflagellation (i.e. male gamete production)

Phenotype
Phenotype analyses of mutants lacking the actin II gene (RMgm-632) indicate that Actin II plays a major role during the formation of the male gametes (no exflagellation of male gametocytes; no male gamete formation)

Mutants in which the actin II is replaced by actin I (act2rep; RMgm-935) show a partly restored exflagellation (i.e. male gamete production)

Phenotype analyses of the actIchi mutant show that in this mutant exflagellation is (nearly) comparable to wild type

Additional information

Other mutants
Mutants lacking the actin II gene (RMgm-632)
Mutants in which the actin II is replaced by actin I (act2rep; RMgm-935) show a partly restored exflagellation (i.e. male gamete production)