Title: Phosphorylation-dependent interaction between the splicing factors SAP155 and NIPP1
Authors: Boudrez, An *
Beullens, Monique *
Waelkens, Etienne
Stalmans, Willy
Bollen, Mathieu # ×
Issue Date: Aug-2002
Publisher: American Society for Biochemistry and Molecular Biology
Series Title: Journal of Biological Chemistry vol:277 issue:35 pages:31834-41
Abstract: NIPP1 is a ubiquitously expressed nuclear protein that functions both as a regulator of protein Ser/Thr phosphatase-1 and as a splicing factor. The N-terminal part of NIPP1 consists of a phosphothreonine-interacting Forkhead-associated (FHA) domain. We show here that the FHA domain of NIPP1 interacts in vitro and in vivo with a TP dipeptide-rich fragment of the splicing factor SAP155/SF3b(155), a component of the U2 small nuclear ribonucleoprotein particle. The NIPP1-SAP155 interaction was entirely dependent on the phosphorylation of specific TP motifs in SAP155. Mutagenesis and competition studies revealed that various phosphorylated TP motifs competed for binding to the same site in the FHA domain. The SAP155 kinases in cell lysates were blocked by the Ca(2+) chelator EGTA and by the cyclin-dependent protein kinase inhibitor roscovitine. The phosphorylation level of SAP155 was dramatically increased during mitosis, and accordingly the activity of SAP155 kinases was augmented in mitotic lysates. We discuss how the interaction between NIPP1 and SAP155 could contribute to spliceosome (dis)assembly and the catalytic steps of splicing.
ISSN: 0021-9258
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Biochemistry Section (Medicine) (-)
Laboratory of Protein Phosphorylation and Proteomics
Department of Cellular and Molecular Medicine - miscellaneous
Laboratory of Biosignaling & Therapeutics
Laboratory of Phosphoproteomics (-)
* (joint) first author
× corresponding author
# (joint) last author

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