The critical role of asparagine 502 in post-translational alteration of protein 4.1.
1. Protein 4.1 in most mammalian red cells exhibits a post-translational conversion of 4.1b to 4.1a, except for feline protein 4.1, which lacks this alteration. 2. Our previous study provided evidence that protein 4.1b in human red cells is converted to 4.1a by deamidation of a specific asparagine (Asn) residue at position 502, suggesting that the post-translational change of 4.1b to 4.1a depends on the primary structure of the protein at the site of deamidation. 3. To confirm this hypothesis, proteolytic fragments corresponding to the deamidation site of human protein 4.1 were purified from canine and feline erythrocyte protein 4.1 and analyzed for their amino acid sequences. 4. Two proteolytic peptides, D7 and D9 derived from canine protein 4.1, both corresponding to the human sequence Thr492-...-Asn (or Asp)502-...-Lys505 showed the same sequence, Thr-Gln-Thr-...-Lys, except that the 11th residue equivalent to the 502nd amino acid was Asn in D7 while it was Asp in D9, indicating that deamidation occurs at the same position in canine protein 4.1 as in humans. 5. However, substitution of Ser for Asn at this position was observed in feline protein 4.1. 6. These results demonstrate that Asn502 has a critical role in post-translational conversion of 4.1b to 4.1a in mammalian red blood cells.
Inaba
M
M
Department of Veterinary Internal Medicine, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Maede
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001216:Asparagine / Q000737:chemistry; D002415:Cats; D003598:Cytoskeletal Proteins; D004285:Dogs; D004910:Erythrocyte Membrane / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009479:Neuropeptides; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D011499:Protein Processing, Post-Translational; D013045:Species Specificity; D013329:Structure-Activity Relationship
D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; D009479:Neuropeptides; D010446:Peptide Fragments; C028841:erythrocyte membrane band 4.1 protein; C120557:erythrocyte membrane protein band 4.1-like 1; D001216:Asparagine