title: Isolation and characterization of a complementary DNA expressing human U1 small nuclear ribonucleoprotein C polypeptide.
abstract: A cloned complementary DNA, termed pS2, was isolated from a human fibroblast cDNA library in the bacteriophage expression vector lambda gt11 after screening with a patient's serum containing a high titer of anti-ribonucleoprotein (RNP) antibodies. A reasonable amount of cro-beta-galactosidase fusion protein (pS2EX) was obtained through subcloning of the pS2 insert into a plasmid expression vector pEX-2. Antibody against pS2EX (anti-pS2EX) was purified from this patient's serum by Sepharose 4B conjugated with pS2EX. Immunofluorescent staining of HeLa cells with anti-pS2EX antibody exhibited a typical speckled pattern in the interphase nuclei. In the immunoblot analysis, the anti-pS2EX antibody recognized the 22 kDa protein. Using immunoprecipitation of cell lysate and subsequent RNA analysis, anti-pS2EX antibody was shown to precipitate U1 RNP only. The reactivities of various anti-RNP sera to pS2EX correlated well with the positive reaction to C polypeptide in the immunoblot. These findings indicate that pS2 is a cDNA for C polypeptide of U1 snRNP. In the Northern blot using human RNA and radiolabeled pS2, a single band about 800 base was observed. The nucleotide sequence of pS2 showed no significant homologies to known proteins.
mesh_terms: D000595:Amino Acid Sequence; D001323:Autoantibodies / Q000276:immunology; D001324:Autoantigens / Q000235:genetics*; D001327:Autoimmune Diseases / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D005455:Fluorescent Antibody Technique; D006801:Humans; D007163:Immunosorbent Techniques; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011993:Recombinant Fusion Proteins / Q000235:genetics; D012261:Ribonucleoproteins / Q000235:genetics*; D017411:Ribonucleoproteins, Small Nuclear
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D011993:Recombinant Fusion Proteins; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; D004247:DNA