(A) The central channel in the apo-PfFNT protomer viewed from the parasite's membrane plane. The channel, calculated by HOLE (Smart et al, 1996), is indicated by blue dots. The two constriction sites are colored red. Residues forming the constriction sites are in green sticks. Residues that line the rest of the channel are in cyan sticks. (B) Representative figure of the calculated diameters of an apo-PfFNT protomer. 