The schematic drawing represents the known key players of the invasion machinery, space filled models represent known structures either from Plasmodium (Bosch et al., 2007b; Bosch et al., 2006a; Bosch et al., 2006b) or in the case of actin (rabbit) and myosin (chicken) (Holmes et al., 2003). The host cell in this case represents an erythrocyte, therefore the transmembrane receptor is MTRAP. In the liver stage this receptor is replaced by TRAP and in the insect stage with CTRP. The N-terminal sequences of TRAP, MTRAP and CTRP vary and have different length but their C-terminus is very similar and harbors one conserved tryptophan adjacent to charged residues. The transmembrane helix of PfGAP50 was modeled by extending the helical sequence. The exact orientation is unknown but evidence of an interaction with the other proteins of the invasion machinery exists e.g. through pull-down assays (Baum et al., 2006; Bergman et al., 2003; Johnson et al., 2007).