title: Deamidation of human erythrocyte protein 4.1: possible role in aging.
abstract: The human erythrocyte membrane protein 4.1 exists in two major electrophoretic forms: 4.1a (80 Kd) and 4.1b (78 Kd). Mass spectrometry and amino acid analysis of the proteolytic peptides derived from carboxyl-terminal regions of these proteins indicate that they differ by deamidation of two aspargine residues at positions 478 and 502. Electrophoretic analysis of carboxyl-terminal peptides has shown that the mobility difference between the two polypeptides is due to the deamidation of Asn502 and not that of Asn478. This observation was confirmed by converting a congener of the protein 4.1b to 4.1a by site-directed mutagenesis of Asn502 to Asp. These results unambiguously demonstrate that deamidation of Asn502 is responsible for conversion of protein 4.1b to 4.1a. Since the conversion of protein 4.1b to 4.1a, under physiological conditions, occurs in a time-dependent manner, our study clearly shows that deamidation is an excellent marker for red blood cell aging.
authors.affiliation: Department of Veterinary Internal Medicine, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Inaba
authors.forename: K C
authors.initials: KC
authors.lastname: Gupta
authors.forename: M
authors.initials: M
authors.lastname: Kuwabara
authors.forename: T
authors.initials: T
authors.lastname: Takahashi
authors.forename: E J
authors.initials: EJ
authors.lastname: Benz
authors.forename: Y
authors.initials: Y
authors.lastname: Maede
mesh_terms: D000595:Amino Acid Sequence; D001216:Asparagine / Q000737:chemistry / Q000378:metabolism; D001224:Aspartic Acid / Q000737:chemistry / Q000378:metabolism; D001483:Base Sequence; D003488:Cyanogen Bromide; D003598:Cytoskeletal Proteins; D004591:Electrophoresis, Polyacrylamide Gel; D004905:Erythrocyte Aging / Q000502:physiology*; D006801:Humans; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009479:Neuropeptides; D010446:Peptide Fragments / Q000737:chemistry; D011499:Protein Processing, Post-Translational; D012697:Serine Endopeptidases / Q000378:metabolism
chemical_list: 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; D001224:Aspartic Acid; D001216:Asparagine; D012697:Serine Endopeptidases; C060325:arginine endopeptidase; D003488:Cyanogen Bromide