| First Author | Miranda TB | Year | 2004 |
| Journal | Biochem Biophys Res Commun | Volume | 323 |
| Issue | 2 | Pages | 382-7 |
| PubMed ID | 15369763 | Mgi Jnum | J:92481 |
| Mgi Id | MGI:3052893 | Doi | 10.1016/j.bbrc.2004.08.107 |
| Citation | Miranda TB, et al. (2004) Spliceosome Sm proteins D1, D3, and B/B' are asymmetrically dimethylated at arginine residues in the nucleus. Biochem Biophys Res Commun 323(2):382-7 |
| abstractText | We report a novel modification of spliceosome proteins Sm D1, Sm D3, and Sm B/B'. L292 mouse fibroblasts were labeled in vivo with [(3)H]methionine. Sm D1, Sm D3, and Sm B/B' were purified from either nuclear extracts, cytosolic extracts or a cytosolic 6S complex by immunoprecipitation of the Sm protein-containing complexes and then separation by electrophoresis on a polyacrylamide gel containing urea. The isolated Sm D1, Sm D3 or Sm B/B' proteins were hydrolyzed to amino acids and the products were analyzed by high-resolution cation exchange chromatography. Sm D1, Sm D3, and Sm B/B' isolated from nuclear fractions were all found to contain omega-N(G)-monomethylarginine and symmetric omega-N(G),N(G')-dimethylarginine, modifications that have been previously described. In addition, Sm D1, Sm D3, and Sm B/B' were also found to contain asymmetric omega-N(G),N(G)-dimethylarginine in these nuclear fractions. Analysis of Sm B/B' from cytosolic fractions and Sm B/B' and Sm D1 from cytosolic 6S complexes showed only the presence of omega-N(G)-monomethylarginine and symmetric omega-N(G),N(G')-dimethylarginine. These results indicate that Sm D1, Sm D3, and Sm B/B' are asymmetrically dimethylated and that these modified proteins are located in the nucleus. In reactions in which Sm D1 or Sm D3 was methylated in vitro with a hemagglutinin-tagged PRMT5 purified from HeLa cells, we detected both symmetric omega-N(G),N(G')-dimethylarginine and asymmetric omega-N(G),N(G)-dimethylarginine when reactions were done in a Tris/HCl buffer, but only detected symmetric omega-N(G),N(G')-dimethylarginine when a sodium phosphate buffer was used. These results suggest that the activity responsible for the formation of asymmetric dimethylated arginine residues in Sm proteins is either PRMT5 or a protein associated with it in the immunoprecipitated complex. |
