Mutant/mutation
The mutant lacks expression of kinesin-X4 and expresses GFP under the constitutive eef1a promoter.

Protein (function)
Kinesins are microtubule (MT)-based motor proteins that use energy from the hydrolysis of ATP and function in various cellular processes including intracellular transport, mitotic spindle formation and chromosome segregation during cell division, and the organisation of cell polarity and cytoskeleton associated with motility.
There are 14-16 kinesin subfamilies identified in eukaryotes, and categorised based on analysis of the motor domain, with similar biological roles established by in vitro studies, and in vivo phenotypes in these organisms . Kinesin subfamilies that regulate MT dynamics, such as kinesin-8 and -13, are found in most eukaryotes including primitive and evolutionarily divergent eukaryotes. 
In a bioinformatic analysis of kinesins in Apicomplexa, nine kinesins encoded in the Plasmodium berghei genome were identified, with members of three conserved kinesin subfamilies (kinesin-5, -8B, -8X and -13); kinesin-4, -15 and -20; and two Apicomplexa-specific kinesins: kinesin-X3 and -X4 (Zeeshan et al., 2019).

X3: PBANKA_060950; PF3D7_1211000
X4: PBANKA_0902400; PF3D7_1146700

From the paper: 
'We elucidate the subcellular location of each kinesin using a protein endogenously tagged at the C-terminus with GFP, showing a differential localisation of kinesins in the mitotic and meiotic stages and a pellicular and polar location in certain invasive stages.  Eight of the nine kinesins are required only for parasite transmission through the mosquito vector during the sexual and asexual sporogony stages. Only kinesin-13 is likely essential during blood stage schizogony. An in-depth analysis of kinesin-13 and kinesin-20 revealed a distinct subcellular location and function in MT assembly during spindle formation, axoneme assembly and cell polarity. Kinesin-20 was associated with a striking ring-like structure during zygote to ookinete differentiation and deletion of the gene revealed a function in the morphology and motility of the ookinete'.

Other mutants