Figure 7. Schematic illustration of the cytosolic Ca²⁺ homeostasis in P. falciparum.

Blood stage parasites observed in in vitro cultures and their estimated cytosolic Ca²⁺ concentrations are indicated. In the trophozoite stage parasite, P. falciparum SERCA (PfATP6) is inhibited by cyclopiazonic acid (CPA) and 2,5-Di-t-butyl-1,4-butylhydroquinone (BHQ), but not by thapsigargin (TG) and dihydroartemisinin (dART). CPA and BHQ may also affect PfATP4, a Na⁺-ATPase located on the parasite plasma membrane (PPM), and inhibit Ca²⁺ influx from parasite cytosol to parasitophorous vacuole. Expected non-ER Ca²⁺-containing compartment(s) with potential integral membrane Ca²⁺ transporters are indicated. Inositol trisphosphate receptor (IP₃R) on the ER membrane has been proposed, but the encoding gene has not been identified⁴.