Mutant/mutation
The mutant lacks expression of a functional CTRP protein (circumsporozoite protein [CSP] and thrombospondin-related adhesive protein [TRAP]-related protein; CSP and TRAP-related protein (CTRP).
By Western analysis of proteins of ookinete preparations with antibodies against CTRP a smaller protein of Mr 190 000 was detected in mutants compared with that detected in wild type parasites. This protein must result from translation of truncated mRNA transcribed from the CTRP gene in the mutants. It is expected to be 266 amino acids smaller as a result of the TgDHFR/TS insertion

Protein (function)
CTRP is a type 1 transmembrane protein, containing two adhesive domains in its extracellular portion, an A-domain of von Willebrand factor and a thrombospondin type I repeat (TSR, TSP). CTRP has six tandemly arrayed A domains followed by seven TSP type 1-like domains. CTRP is located in the micronemes of ookinetes. This structure is similar to that of TRAP (PF13_0201; PB000374.03.0), a malaria sporozoite protein critical for sporozoite motility and invasion into host cells.
CTRP plays a role in the motility of ookinetes and invasion of midgut epithelial cells.

Phenotype
The phenotype analyses indicate a role in the transformation of the ookinete into the oocyst. This and other studies indicate a role in motility and invasion of midgut epithelial cells.

Additional information
Ookinetes lacking expression of CTRP that are directly injected into the hemocoel, thereby by-passing the midgut wall, develop into oocysts and these ookinetes can transform in vitro into oocysts, indicating that CTRP is not essential for transformation of ookinetes into oocysts (Nacer, A. et al., Malar J.  19;7:82).

A P. falciparum mutant lacking CTRP (PFC0640w) has been generated which show a comparable defect in the formation of oocysts (Templeton, T.J. 2000. Mol. Microbiol. 36, 1-9. 

A mutant has been generated (RMgm-150) that expresses a mutated form of TRAP (thrombospondin-related anonymous protein; PB000374.03.0; PF13_0201), in which the cytoplasmic tail domain (CTD) of TRAP is replaced with the CTD domain of CTRP. The CTD of CTRP can complement the function of the CTD of TRAP, albeit not as well as TRAP as shown by the reduced invasion of salivary glands and hepatocytes. 

Other mutants
RMgm-140:  An independent mutant lacking expression of CTRP.
RMgm-150: A mutant that expresses a mutated form of TRAP (thrombospondin-related anonymous protein; PB000374.03.0; PF13_0201), in which the cytoplasmic tail domain (CTD) of TRAP is replaced with the CTD domain of CTRP.