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The snRNP-free U1A (SF-A) complex(es): Identification of the largest subunit as PSF, the polypyrimidine-tract binding protein-associated splicing factor

Published online by Cambridge University Press:  01 December 1998

CAROL S. LUTZ ,
CHARLES COOKE ,
J. PATRICK O'CONNOR ,
RYUJI KOBAYASHI  and
JAMES C. ALWINE
CAROL S. LUTZ
Affiliation:
Department of Microbiology, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania 19104, USA Present address: Department of Biochemistry and Molecular Biology, UMDNJ-New Jersey Medical School, Newark, New Jersey 07103, USA.
CHARLES COOKE
Affiliation:
Department of Microbiology, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania 19104, USA
J. PATRICK O'CONNOR
Affiliation:
Department of Orthopaedics, UMDNJ-New Jersey Medical School, Newark, New Jersey 07103, USA
RYUJI KOBAYASHI
Affiliation:
Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
JAMES C. ALWINE
Affiliation:
Department of Microbiology, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania 19104, USA
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Abstract

We have previously shown that a specific monoclonal antibody prepared against the U1A protein, MAb 12E12, is unique in its ability to recognize a form of U1A which is not associated with the U1snRNP. This unique form of U1A, termed snRNP-free U1A or SF-A, was found to be complexed with a novel set of non-snRNP proteins (O'Connor et al., 1997, RNA 3:1444-1455). Here we demonstrate that the largest protein in these SF-A complex(es), p105, is the polypyrimidine-tract binding protein-associated factor (PSF), an auxiliary splicing factor. We show that PSF copurifies and co-immunoprecipitates with SF-A from 293T cell nucleoplasm and that it interacts with SF-A in vitro. In addition, we show that MAb 12E12 inhibits both splicing and polyadenylation in an in vitro coupled splicing and polyadenylation reaction. This suggests that SF-A and/or the SF-A complex(es) perform an important function in both processing reactions and possibly in last exon definition.

Keywords

polyadenylationRNA processingSF-A complexsnRNP-free U1A (SF-A)splicingU1snRNP
Type
Research Article
Information
RNA , Volume 4 , Issue 12 , December 1998 , pp. 1493 - 1499
Copyright
© 1998 RNA Society

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