title: Molecular relationships between U snRNP proteins as investigated by rabbit antisera and peptide mapping.
abstract: Each of the major U snRNP polypeptides from human cells was purified by electroelution from SDS-polyacrylamide gels. Rabbit antisera could be obtained against the individual proteins 70K, A, B', B and D, although rabbits failed to elicit antibodies against E, F and G. A strong structural homology was found between proteins B' and B, against which patients with connective tissue diseases produce predominantly anti-Sm autoantibodies. Thus, rabbit antisera against B' strongly crossreact with B and vice versa. Peptide patterns of the proteins B' and B obtained with chymotrypsin are identical with the exception of one fragment in each case. Polypeptide D, the third major Sm-antigenic protein, is structurally distinct from B' and B, as evidenced by the failure of anti-D antisera to crossreact with B' or B and vice versa, as well as by the different peptide patterns observed for proteins D and B' or B. The U1 specific polypeptide A and the U2 specific polypeptide B" share homologous regions, as indicated by the crossreactivity of anti-A antisera with protein B", and the occurrence of common fragments in the peptide patterns of the two proteins. Further homologies between other snRNP protein pairs were not detected.
mesh_terms: D000818:Animals; D001324:Autoantigens / Q000235:genetics* / Q000276:immunology; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000235:genetics / Q000276:immunology; D006801:Humans; D007106:Immune Sera; D010449:Peptide Mapping; D010455:Peptides / Q000276:immunology; D011817:Rabbits; D012261:Ribonucleoproteins / Q000235:genetics* / Q000276:immunology; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins
chemical_list: D001324:Autoantigens; D000939:Epitopes; D007106:Immune Sera; D010455:Peptides; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins