Molar concentrations of sorbitol and polyethylene glycol inhibit the Plasmodium aquaglyceroporin but not that of E. coli: Involvement of the channel vestibules

► Plasmodium falciparum PfAQP conducts water, E. coli EcGlpF does not. ► Sorbitol inhibits PfAQP water and glycerol permeability but not that of EcGlpF. ► The extracellular vestibule of PfAQP is a possible binding site for sorbitol. ► PfAQP prefers glycerol when exposed to mixed hypertonic glycerol-urea gradients.