AMINO-ACID-SEQUENCES AROUND EXOFACIAL PROTEOLYTIC CLEAVAGE SITES OF BAND-3 FROM BOVINE AND PORCINE ERYTHROCYTES

1. Amino acid sequences of bovine and porcine band 3, an erythrocyte a nion transporter, were determined. 2. The sequence of bovine band 3 wa s positioned to residues 519-599 (the numbering is based on human band 3), in which probably 6 residues were unidentified. 3. Binding site o f DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonate), a potent anion transport inhibitor, was identified as Lys-539 in the bovine case. 4. A loop (residues 551-567), which provides exofacial proteolytic cleava ge sites, contains only 53% homology between human and bovine, whereas the residues flanking it on either side are > 84% homologous. 5. Furt hermore, the loop of porcine band 3 was indicated to consist of a 6 or 7-residues short peptide as compared with those of other species.