The physiological properties of the band 3 anion exchanger as derived from pH and other studies with human red cells.

The kinetics of the erythrocyte anion exchanger which have been studied at high pH values have confirmed the importance of hydroxyl ions in the overall physiological roles of the band 3 protein in human red cells. Although usually characterised as a one-for-one anion exchanger, conditions have been identified which give the appearance of net transport. The present findings have uncovered new functional features consistent with the properties of anion transport in other tissues. The molecular models proposed to interpret the results could have wider applications to other cellular mechanisms. Some of these are discussed to illustrate the physiological implications which can be deduced from the novel kinetics of this unique membrane transport protein.