| First Author | Llorian M | Year | 2004 |
| Journal | Biochem J | Volume | 378 |
| Issue | Pt 1 | Pages | 229-38 |
| PubMed ID | 14640981 | Mgi Jnum | J:88011 |
| Mgi Id | MGI:3028820 | Doi | 10.1042/BJ20030950 |
| Citation | Llorian M, et al. (2004) SIPP1, a novel pre-mRNA splicing factor and interactor of protein phosphatase-1. Biochem J 378(Pt 1):229-38 |
| abstractText | We have identified a polypeptide that was already known to interact with polyglutamine-tract-binding protein (PQBP)-1/Npw38 as a novel splicing factor and interactor of protein phosphatase-1, hence the name SIPP1 for splicing factor that interacts with PQBP-1 and PP1 (protein phosphotase 1). SIPP1 was inhibitory to PP1, and its inhibitory potency was increased by phosphorylation with protein kinase CK1. Two-hybrid and co-sedimentation analysis revealed that SIPP1 has two distinct PP1-binding domains and that the binding of SIPP1 with PP1 involves a RVXF (Arg-Val-Xaa-Phe) motif, which functions as a PP1-binding sequence in most interactors of PP1. Enhanced-green-fluorescent-protein-tagged SIPP1 was targeted exclusively to the nucleus and was enriched in the nuclear speckles, which represent storage/assembly sites of splicing factors. We have mapped a nuclear localization signal in the N-terminus of SIPP1, while the proline-rich C-terminal domain appeared to be required for its subnuclear targeting to the speckles. Finally, we found that SIPP1 is also a component of the spliceosomes and that a SIPP1-fragment inhibits splicing catalysis by nuclear extracts independent of its ability to interact with PP1. |
