1.A.91.1.1
The plasmodial three-component surface broad specificity anion channel complex. One component is PSAC (Clag3.2, Clag3/2, RhopH1, of 1416 aas and at least two putative TMSs, one N-terminal and one C-terminal (residues 1199 to 1223)). The latter is an amphipathic α-helix thought to form the channel in the multisubunit complex (Sharma et al. 2015).  CLAG3 undergoes hetero-association, and its expression determines the channel phenotype quantitatively, leading to host erythrocyte permeability to ions and nutrients (Gupta et al. 2018). The isoforms traffic to and insert in the host membrane while remaining associated with two unrelated parasite proteins, RhopH2 (CLAG3.2 of 1414 aas (B0M163) and RhopH3   (CLAG3.3 (B0M0W2) of 897 aas and up to 4 TMSs, one N-terminal and up to three centrally located. Both the channel phenotypes and molecular changes are consistent with a multiprotein complex that forms the nutrient pore, supporting direct involvement of the CLAG3 protein in channel formation (Gupta et al. 2018). Inhibitors potentially useful theraputically at 5 μM concentrations include PRT1-20 and ISPA-28. Their use suggested that there may be two routes of nutrient entry via the PSAC (Pain et al. 2016). Reviewed by Meier et al. 2018. Malaria parasites use a soluble RhopH complex for erythrocyte invasion and an integral membrane channel form for nutrient uptake (Schureck et al. 2021). (See family description for more details.) The kinetics of CLAG3.2 insertion into the erythrocyte membrane has been studied (Shao et al. 2022).  Ion channel proteins in P. falciparum have been reviewed (Desai 2024).