To analyse whether the transporters facilitate H + or OH -transport predominantly via the fatty acid flip-flop mechanism or fatty acid independent mechanisms (e.g., transporter deprotonation or OH -transport), the fatty acids are sequestered from the vesicle membrane by treatment with bovine serum albumin (BSA, Figure ). The removal of the fatty acids embedded in the membrane prevents fatty acid flip-flop assisted H + transport (however, it should be noted that the BSA-fatty acid-binding is a dynamic equilibrium, and the traces of residual free fatty acids after BSA treatment can still contribute to a fatty acid-dependent H + transport pathway). A reduced pH dissipation rate in the presence of BSA indicates a fatty acid-dependent H + transport mechanism for the anion transporter. However, additional control experiments may be required to rule out BSA-transporter interactions that could also result in reduced transport rates.