Mutations in band 3 and cation leaky red cells.

We have recently shown that amino acid substitutions in the membrane domain of band 3 (anion exchanger 1, SLC4A1) are associated with hereditary stomatocytosis (HSt), a red cell condition in which the cells leak sodium and potassium ions. These substitutions appear to convert band 3 from an anion exchanger into a cation channel. In this review, I will first give some background on the structure and function of normal band 3 and describe our findings in red cells from HSt patients. Then I will compare the properties of the HSt band 3 to those of Southeast Asian Ovalocytosis (SAO) band 3 and discuss the implications for the structure of band 3, the quality control of protein expression in red cells and the cation permeability of normal human red cells.