Title: SIPP1, a novel pre-mRNA splicing factor and interactor of protein phosphatase-1
Authors: Llorian, Miriam ×
Beullens, Monique
Andrés, Isabel
Ortiz, Jose-Miguel
Bollen, Mathieu #
Issue Date: Feb-2004
Publisher: Published by Portland Press on behalf of the Biochemical Society
Series Title: Biochemical Journal vol:378 issue:Pt 1 pages:229-38
Abstract: 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.
ISSN: 0264-6021
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Biochemistry Section (Medicine) (-)
Laboratory of Biosignaling & Therapeutics
× corresponding author
# (joint) last author

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