Mutant/mutation
The mutant lacks expression of Pk9 and expresses GFP

Protein (function)
Previous studies have shown that functionally Pk9 can be designated as a serine-threonine kinase (STK) owing to its ability to phosphorylate E2 conjugation enzyme at serine 106 residue of Ubc13, although it does not cluster with any established eukaryotic protein kinase groups and hence is referred to as orphan kinase.

Phenotype
Normal, wild-type-like development throughout the complete life cycle

Additional information
 In this study also evidence is presented that that phosphorylation of the regulatory serine 106 of Ubc13 is essential for the completion of the parasite’s erythrocytic cycle. However,  phosphorylated form of Ubc13 was observed in Pk9 knockout parasites.

The process of ubiquitylation typically requires three enzymes: E1 (ubiquitin-activating enzyme, Uba), E2 (ubiquitin-conjugating enzyme, Ubc), and E3 (ubiquitin-protein ligase). Amongst Ubcs, Ubc13 specifically catalyzes the formation of K63-linked ubiquitin chains that are critical to signaling in inflammatory and DNA damage response pathways.

See also mutant RMgm-5208 with a mutated UNC13 (the phosphorylating serine 106 replaced with with non-phosphorylatable alanine).

Other mutants