title: Two-dimensional iodopeptide mapping demonstrates that erythrocyte Rh D, c, and E polypeptides are structurally homologous but nonidentical.
abstract: The 32,000 molecular weight (mol wt) erythrocyte Rh D, c, and E polypeptides were separately purified from cDE/cDE erythrocytes by monoclonal immunoprecipitations and compared by two-dimensional iodopeptide mapping. Digestions of the isolated Rh polypeptides with alpha-chymotrypsin revealed a high degree of structural homology between c and E (13/14 iodopeptides were identical) and less striking homology between D and c or E (8/19 identical). The iodopeptide maps of Rh proteins purified by a nonimmunologic protocol from cDE/cDE erythrocytes were virtually identical to the composite pattern (D + c + E) deduced from the individual maps of Rh D, c, and E iodopeptides. Digestions of the isolated Rh polypeptides with trypsin revealed an overall homology of approximately 50% between iodopeptides derived from D, c, and E. These data indicate that the erythrocyte Rh D, c, and E antigens are carried by homologous but distinct molecular species; c and E appear more closely related to each other than to D.
mesh_terms: D000941:Antigens / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007467:Iodoproteins / Q000302:isolation & purification*; D010446:Peptide Fragments / Q000302:isolation & purification; D010449:Peptide Mapping; D011233:Precipitin Tests; D012204:Rh-Hr Blood-Group System / Q000235:genetics / Q000302:isolation & purification; D012689:Sequence Homology, Nucleic Acid
chemical_list: D000941:Antigens; D007467:Iodoproteins; D010446:Peptide Fragments; D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen