A coactivator of pre-mRNA splicing
Abstract
The nuclear matrix antigen recognized by the monoclonal antibody (mAb) B1C8 is a novel serine (S) and arginine (R)-rich protein associated with splicing complexes and is named here SRm160 (SR-related matrix protein of160 kD). SRm160 contains multiple SR repeats, but unlike proteins of the SR family of splicing factors, lacks an RNA recognition motif. SRm160 and a related protein SRm300 (the 300-kD nuclear matrix antigen recognized by mAb B4A11) form a complex that is required for the splicing of specific pre-mRNAs. The SRm160/300 complex associates with splicing complexes and promotes splicing through interactions with SR family proteins. Binding of SRm160/300 to pre-mRNA is normally also dependent on U1 snRNP and is stabilized by U2 snRNP. Thus, SRm160/300 forms multiple interactions with components bound directly to important sites within pre-mRNA. The results suggest that a complex of the nuclear matrix proteins SRm160 and SRm300 functions as a coactivator of pre-mRNA splicing.
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Footnotes
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Present addresses: 3C.H. Best Institute, University of Toronto, Toronto, Ontario, Canada, M5G 1L6; 4Ariad Pharmaceuticals, Cambridge, Massachusetts 02139 USA.
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↵Corresponding author.
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E-MAIL sharppa{at}mit.edu; FAX (617) 253-3867.
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- Received September 30, 1997.
- Accepted January 29, 1998.
- Cold Spring Harbor Laboratory Press