Mutant/mutation
The mutant lacks expression of NEK4 protein and expresses GFP under the control of the eef1a promoter. The mutant has been generated using the same DNA construct to generate the published mutant RMgm-59.

Protein (function)
NEK4 is a serine/threonine NIMA-related kinase; these kinases are mostly described as being involved in controlling/coordinating signalling processes in mitosis. See RMgm-59, RMgm-60 for a description of the phenotype of mutants lacking expression of NEK4. In these mutants gamete formation is not affected. Fertilisation occurs, but development is arrested at 2N zygote stage. The defect is female gamete specific; male gametes are fertile and able to fertilize wild-type female gametes.

The NIMA-related protein kinases (Neks) constitute an extended family of eukaryotic mitotic serine/threonine kinases. The best characterized members of the Nek family include NIMA (never in mitosis/Aspergillus), the founding member from the fungus Aspergillus nidulans, and its closest homologue in mammals, Nek2. Initially identified as a kinase essential for mitotic entry in Aspergillus, NIMA has been also shown to participate in nuclear membrane fission. Eleven members of the NIMA kinase family (Nek1-11) have now been identified in various human tissues, and together fulfil a number of cell cycle-related functions in centrosome separation, mitosis, meiosis and checkpoint control. The P. falciparum kinome includes four NIMA-related serine/threonine kinases. Pfnek-1 (PlasmoDB identifier PFL1370w) clusters within the Aspergillus NIMA/human Nek2 branch in phylogenetic trees, while clear orthology to mammalian or yeast Neks could not be assigned for the three other P. falciparum sequences (Pfnek-2, -3 and -4, PlasmoDB identifiers PFE1290w, PFL0080c and MAL7P1.100,respectively).

Phenotype
The phenotype has not been analysed in detail. See RMgm-59, RMgm-60 for a detailed description of the phenotype of mutants lacking NEK4. This mutant has been generated in a parent P. berghei reference line that expresses GFP constitutively throughout the life cycle (RMgm-7) using the same DNA construct to generate mutant RMgm-59. The mutant can be obtained from the Leiden Malaria Research Group.

Since mutants lacking expression of NEK4 produce fertile males and infertile females, these mutants can be used in cross-fertilisation studies for the analysis of female gamete fertility of other mutants.

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.