FIGURE 7.

Working molecular model for FREP1-mediated Plasmodium parasite invasion in Anopheline mosquitoes. After a blood meal, FREP1 is secreted into mosquito midgut lumen and associated with the newly formed PM. PM-associated tetrameric FREP1 binds a putative FREP1-binding partner(s) expressed on the surface of Plasmodium parasites, thereby anchoring the parasite within the PM. Stoichiometry of these interactions is under investigation. Continuous secretion of chitinase by anchored ookinetes digests chitin in PM, which results in disruption of PM. Dissolution of the PM enables ookinetes to eventually escape and overcome the PM barrier and subsequently invade the midgut epithelium.