Related Experiment Videos
Phosphorylation-dependent interaction between the splicing factors SAP155 and NIPP1
An Boudrez1, Monique Beullens, Etienne Waelkens
1Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium.
The Journal of Biological Chemistry
|July 10, 2002
Summary
Nuclear protein NIPP1 binds to splicing factor SAP155 via its FHA domain, dependent on SAP155 phosphorylation. This interaction, regulated by kinases, is crucial for spliceosome function during mitosis.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Nuclear protein NIPP1 regulates protein phosphatase-1 and splicing.
- NIPP1 possesses a Forkhead-associated (FHA) domain that interacts with phosphothreonine.
- SAP155/SF3b(155) is a component of the U2 small nuclear ribonucleoprotein particle involved in splicing.
Purpose of the Study:
- To investigate the interaction between NIPP1 and SAP155.
- To determine the role of SAP155 phosphorylation in this interaction.
- To elucidate the functional implications of the NIPP1-SAP155 interaction in spliceosome dynamics.
Main Methods:
- In vitro and in vivo interaction assays.
- Mutagenesis and competition studies.
- Analysis of SAP155 phosphorylation levels and kinase activity during the cell cycle.
Main Results:
- The FHA domain of NIPP1 directly interacts with a TP dipeptide-rich fragment of SAP155.
- This interaction is strictly dependent on the phosphorylation of specific TP motifs within SAP155.
- SAP155 phosphorylation and associated kinase activity are significantly elevated during mitosis.
Conclusions:
- The NIPP1-SAP155 interaction is mediated by phosphorylated TP motifs binding to the NIPP1 FHA domain.
- Kinase activity regulating SAP155 phosphorylation is modulated by cell cycle, particularly mitosis.
- This interaction likely plays a role in spliceosome assembly/disassembly and catalytic splicing steps.