Band 3-Memphis is associated with a lower transport rate of phosphoenolpyruvate

Band 3-Memphis is the most common variant of erythrocyte band 3 protein, in which a single amino acid substitution (Lys56-->Glu) in a cytoplasmic domain of band 3 has been found. We showed here that the prevalence of the variant was particularly higher in the Japanese population than that in other populations. The calculated gene frequency of the variant in Japanese was 0.156, which was about 4 times higher than that in Caucasian. Although it has been generally accepted that the cytoplasmic domain of band 3 bears no relation to anion transport activity, we found that the transport rate of phosphoenolpyruvate in erythrocytes of homozygotes was decreased to about 80% of that in control cells, and that of heterozygotes was at an intermediate level. The evidence indicates that some structural changes in the cytoplasmic domain of band 3 may have influence on the conformation of anion transport system.