Mutant/mutation
In the mutant the endogenous P. berghei TRAP is replaced by P. falciparum TRAP (thrombospondin-related anonymous protein).

Protein (function)
TRAP 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). TRAP is located in the micronemes of sporozoites. The protein plays a role in the gliding motility of sporozoites and invasion of host cells as has been shown by analysis of mutant parasites lacking expression of TRAP (RMgm-47; RMgm-53).

Phenotype
Analysis of the phenotype of the mutant show that P. falciparum TRAP can complement the function of P. berghei TRAP. However, the phenotype analyses indicate that the replacement impairs both the gliding motility and infectivity of the sporozoites as is discussed by Menard and Nussenzweig (2000, Parasitol. Today, 16, 222-24). In the same study mutants has been generated that contain mutated forms of the trap gene of P. falciparum carrying amino acid substitutions or deletions in the adhesive domains. Mutations in the A-domain affect invasion of salivary glands but has no effect on gliding motility or invasion of hepatocytes. Mutations in the TSP (TSR) domain affects both gliding motility and invasion of salivary glands but not invasion of hepatocytes. These results are (partly) in contradiction with results obtained with other mutants that contain mutated A-domains and TSR domains (A-domain: RMgm-49; TSR domain: RMgm-50; RMgm-51; A-domain and TSR domain: RMgm-52). As discussed by Menard and Nussenzweig (2000, Parasitol. Today, 16, 222-24) several methodological problems of heterologous expression of TRAP may limit the validity of the conclusions based on expression of mutated P. falciparum genes in P. berghei. The role of the different domains of the protein in motility and invasion has been analysed in other mutant parasites expressing mutated forms of TRAP (see below).

Other mutants
P. berghei mutants have been generated with mutated cytoplasmic tails of TRAP (RMgm-54; RMgm-55; RMgm-RMgm-56; RMgm-57; RMgm-149; RMgm-150; RMgm-151).
Other P. berghei mutants have been generated with mutated extracellular (adhesive) domains (A-domain: RMgm-48; RMgm-49; TSR domain: RMgm-50; RMgm-51; A-domain and TSR domain: RMgm-52).