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.
Skip Nav Destination
Article navigation
Research Article|
February 15 2004
SIPP1, a novel pre-mRNA splicing factor and interactor of protein phosphatase-1
Miriam LLORIAN;
Miriam LLORIAN
*Departamento de Biologia Molecular, Facultad de Medicina, Universidad de Cantabria, Unidad Asociada al CIB-CSIC, 39011 Santander, Spain
Search for other works by this author on:
Monique BEULLENS;
Monique BEULLENS
†Division of Biochemistry, Faculty of Medicine, Catholic University of Leuven, Herestraat 49, B-3000 Leuven, Belgium
Search for other works by this author on:
Isabel ANDRÉS;
Isabel ANDRÉS
*Departamento de Biologia Molecular, Facultad de Medicina, Universidad de Cantabria, Unidad Asociada al CIB-CSIC, 39011 Santander, Spain
Search for other works by this author on:
Jose-Miguel ORTIZ;
Jose-Miguel ORTIZ
*Departamento de Biologia Molecular, Facultad de Medicina, Universidad de Cantabria, Unidad Asociada al CIB-CSIC, 39011 Santander, Spain
Search for other works by this author on:
Mathieu BOLLEN
Mathieu BOLLEN
1
†Division of Biochemistry, Faculty of Medicine, Catholic University of Leuven, Herestraat 49, B-3000 Leuven, Belgium
1To whom correspondence should be addressed (e-mail Mathieu.Bollen@med.kuleuven.ac.be).
Search for other works by this author on:
Publisher: Portland Press Ltd
Received:
June 25 2003
Revision Received:
November 10 2003
Accepted:
November 27 2003
Accepted Manuscript online:
December 01 2003
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2004
2004
Biochem J (2004) 378 (1): 229–238.
Article history
Received:
June 25 2003
Revision Received:
November 10 2003
Accepted:
November 27 2003
Accepted Manuscript online:
December 01 2003
Citation
Miriam LLORIAN, Monique BEULLENS, Isabel ANDRÉS, Jose-Miguel ORTIZ, Mathieu BOLLEN; SIPP1, a novel pre-mRNA splicing factor and interactor of protein phosphatase-1. Biochem J 15 February 2004; 378 (1): 229–238. doi: https://doi.org/10.1042/bj20030950
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Captcha Validation Error. Please try again.