Amino acid sequence of the N alpha-terminal 201 residues of human erythrocyte membrane band 3.
We have determined the amino acid sequence of the N alpha-terminal portion of band 3, the anion transport protein of the human erythrocyte membrane. The material analyzed was a 201-residue, 23,053-Da fragment cleaved from the cytoplasmic end of band 3 by S-cyanylation. The sequence had these notable features. 1) The N alpha-terminal region was extraordinarily acidic, second only to a segment of similar size from the sigma factor of Escherichia coli RNA polymerase. The first 33 residues contained 6 aspartic acid and 12 glutamic acid residues, no basic residue, and a blocked N alpha-amino group. 2) The first 11 residues of the protein had a striking resemblance to the following 11 residues. 3) In contrast to the acidic N alpha-terminal third, the COOH-terminal two-thirds of the 23,053-Da fragment had a predominantly basic character. The highly acidic character of the N alpha-terminal portion of band 3 accounts for the capacity of this part of the protein to bind glycolytic enzymes in a highly electrostatic fashion, presumably through interaction with their cationic substrate-binding sites.
D000595:Amino Acid Sequence; D001457:Anion Exchange Protein 1, Erythrocyte; D001798:Blood Proteins; D006801:Humans; D010446:Peptide Fragments / Q000032:analysis; D010447:Peptide Hydrolases; D011487:Protein Conformation
D001457:Anion Exchange Protein 1, Erythrocyte; D001798:Blood Proteins; D010446:Peptide Fragments; D010447:Peptide Hydrolases