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The SRm160/300 splicing coactivator subunits

Published online by Cambridge University Press:  01 January 2000

BENJAMIN J. BLENCOWE
Affiliation:
Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Banting and Best Department of Medical Research, C.H. Best Institute, University of Toronto, Toronto, Ontario M5G 1L6, Canada
GÖRAN BAURÉN
Affiliation:
Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Present address: Department of Molecular Genome Research, Stockholm University, S-106 91 Stockholm, Sweden.
ADAM G. ELDRIDGE
Affiliation:
Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Banting and Best Department of Medical Research, C.H. Best Institute, University of Toronto, Toronto, Ontario M5G 1L6, Canada Present address: Departments of Pathology and Microbiology, Stanford University School of Medicine, Stanford, California 94305, USA.
ROBBYN ISSNER
Affiliation:
Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Present address: Ariad Pharmaceuticals, Cambridge, Massachusetts 02139, USA.
JEFFREY A. NICKERSON
Affiliation:
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
EMANUEL ROSONINA
Affiliation:
Banting and Best Department of Medical Research, C.H. Best Institute, University of Toronto, Toronto, Ontario M5G 1L6, Canada
PHILLIP A. SHARP
Affiliation:
Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Abstract

The SRm160/300 splicing coactivator, which consists of the serine/arginine (SR)-related nuclear matrix protein of 160 kDa and a 300-kDa nuclear matrix antigen, functions in splicing by promoting critical interactions between splicing factors bound to pre-mRNA, including snRNPs and SR family proteins. In this article we report the isolation of a cDNA encoding the 300-kDa antigen and investigate the activity of it and SRm160 in splicing. Like SRm160, the 300-kDa antigen contains domains rich in alternating S and R residues but lacks an RNA recognition motif; the protein is accordingly named “SRm300.” SRm300 also contains a novel and highly conserved N-terminal domain, several unique repeated motifs rich in S, R, and proline residues, and two very long polyserine tracts. Surprisingly, specific depletion of SRm300 does not prevent the splicing of pre-mRNAs shown previously to require SRm160/300. Addition of recombinant SRm160 alone to SRm160/300-depleted reactions specifically activates splicing. The results indicate that SRm160 may be the more critical component of the SRm160/300 coactivator in the splicing of SRm160/300-dependent pre-mRNAs.

Type
Research Article
Copyright
© 2000 RNA Society

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