Primary structure of the cytoplasmic domain of human erythrocyte protein band 3. Comparison with its sequence in the mouse.

We report here the peptide profile of the human cytoplasmic domain of band 3 protein (CDB-3). The peptide alignment was designed allowing for maximal homology with the murine protein whose sequence was deduced from cDNA analysis by Kopito and Lodish (Kopito, R.R., Anderson, M. and Lodish, H.F. (1987) J. Biol. Chem. 262, 8035-8040). In the human protein, part of the amino acid sequence has been determined by Kaul et al. (Kaul, R.K., Murthy, P.S.N., Reddy, A.G., Steck. T.L. and Kohler, H. (1983) J. Biol. Chem. 258, 7981-7990). We have sequenced most of the fragment not described by these author. The homology with the murine protein is high (90%), except in a few peptides where it is only 50%. The actual miniaturization of the techniques allows for the determination of a clear peptide profile of human CDB-3 starting from 10 ml blood samples. Our characterization of the peptide profile of membrane proteins is the first step towards the identification of genetic mutations, which have to be looked for in hemolytic anemia when the presence of an abnormal membrane protein is suspected.