title: Heterogeneous nuclear ribonucleoproteins: role in RNA splicing.
abstract: Splicing in vitro of a messenger RNA (mRNA) precursor (pre-mRNA) is inhibited by a monoclonal antibody to the C proteins (anti-C) of the heterogeneous nuclear RNA (hnRNA)-ribonucleoprotein (hnRNP) particles. This antibody, 4F4, inhibits an early step of the reaction: cleavage at the 3' end of the upstream exon and the formation of the intron lariat. In contrast, boiled 4F4, or a different monoclonal antibody (designated 2B12) to the C proteins, or antibodies to other hnRNP proteins (120 and 68 kilodaltons) and nonimmune mouse antibodies have no inhibitory effect. The 4F4 antibody does not prevent the adenosine triphosphate-dependent formation of a 60S splicing complex (spliceosome). Furthermore, the 60S splicing complex contains C proteins, and it can be immunoprecipitated with 4F4. Depletion of C proteins from the splicing extract by immunoadsorption with either of the two monoclonal antibodies to the C proteins (4F4 or 2B12) results in the loss of splicing activity, whereas mock-depletion with nonimmune mouse antibodies bodies has no effect. A 60S splicing complex does not form in a C protein-depleted nuclear extract. These results indicate an essential role for proteins of the hnRNP complex in the splicing of mRNA precursors.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000276:immunology*; D006367:HeLa Cells; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D006801:Humans; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D012326:RNA Splicing; D012332:RNA, Heterogeneous Nuclear / Q000378:metabolism; D012261:Ribonucleoproteins / Q000276:immunology / Q000502:physiology*
chemical_list: D000911:Antibodies, Monoclonal; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D046911:Macromolecular Substances; D012332:RNA, Heterogeneous Nuclear; D012261:Ribonucleoproteins; D000255:Adenosine Triphosphate