Taken together, the bulk of the evidence suggests that altered DV pH for CQR parasites is an indirect consequence of altered osmolyte traffic promoted by PfCRT mutation. This might be an explanation for why parasites treated in different ways (resulting in various levels of relevant osmolytes produced by a finely tuned metabolism) could perhaps show different DV pH in some studies [81, 84] . If altered osmolyte traffic that then indirectly perturbs normal pH regulation is the explanation for altered DV physiology future science group linked to PfCRT mutations, it begs the obvious question: what is the normal physiological function of PfCRT? An obvious attractive possibility suggested early on is that PfCRT might transport products of Hb digestion (peptides, dipeptides and/or free amino acids) [73, 22] , since these are among the most important DV osmolytes, since products of Hb digestion are unique osmolytes and PfCRT is a unique transporter with a unique sequence, and because when CQ, QN and other drugs are superimposed upon amino acid structures (e.g., CQ vs the cationic amino acid lysine), many interesting similarities can be noted. For example, the superposition (overlay) of a dipeptide N-terminal lysine (a common Hb amino acid) and CQ shows similar charge and a similar carbon chain flanked by nitrogen atoms. As another example, an OH group is bound to one chiral center of QN that is two s bonds away from the positively charged quinuclidine nitrogen, and a near identical spatial arrangement of stereochemically sensitive atoms is also found for one isomer of serine. Interestingly, QN and QD differ in their stereochemistry at this center yet show different PfCRT-isoform dependent pharma cology [57] . Perhaps not coincidentally then, if PfCRT did transport peptides or amino acids, substrate recognition would also be stereo-selective since only l-amino acids are found in Hb.