Cef1p Is a Component of the Prp19p-associated Complex and Essential for Pre-mRNA Splicing*
- Wei-Yü Tsai‡§,
- Y-Ting Chow§¶,
- Hau-Ren Chen‡§,
- Kuang-Tse Huang§‖,
- Rong-I Hong‡§**,
- Shr-Peng Jan‡§,
- Nien-Yuan Kuo‡§,
- Twee Y. Tsao‡§,
- Chun-Hong Chenठand
- Soo-Chen Cheng‡§‡
- From the ‡Institute of Microbiology and Immunology, National Yang-Ming University Shih-Pai, Taiwan, Republic of China and the §Institute of Molecular Biology, Academia Sinica, Nankang, Taiwan, Republic of China
Abstract
The Prp19p protein of the budding yeastSaccharomyces cerevisiae is an essential splicing factor and is associated with the spliceosome during the splicing reaction. We have previously shown that Prp19p is not tightly associated with small nuclear ribonucleoprotein particles but is associated with a protein complex consisting of at least eight protein components. By sequencing components of the affinity-purified complex, we have identified Cef1p as a component of the Prp19p-associated complex, Ntc85p. Cef1p could directly interact with Prp19p and was required for pre-mRNA splicing both in vivo and in vitro. The c-Myb DNA binding motif at the amino terminus of Cef1p was required for cellular growth but not for interaction of Cef1p with Prp19p or Cef1p self-interaction. We have identified a small region of 30 amino acid residues near the carboxyl terminus required for both cell viability and protein-protein interactions. Cef1p was associated with the spliceosome in the same manner as Prp19p, i.e. concomitant with or immediately after dissociation of U4. The anti-Cef1p antibody inhibited binding to the spliceosome of Cef1p, Prp19p, and at least three other components of the Prp19p-associated complex, suggesting that the Prp19p-associated complex is likely associated with the spliceosome and functions as an integral complex.
Footnotes
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↵* This work was supported by a grant from the Academia Sinica and by National Science Council (Taiwan) Grant NSC85-2311-B-001-033.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵¶ Present address: School of Chemical Engineering, Cornell University, Ithaca, NY 14853.
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↵‖ Present address: Dept. of Chemical Engineering, Texas A & M University, College Station, TX 77843-3122.
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↵** Present address: Laboratory of Molecular Biophysics, University of Oxford, Oxford OX1 3QU, United Kingdom.
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↵‡ To whom correspondence should be addressed. Tel.: 886-2-2789-9200; Fax: 886-2-2782-6085; E-mail:mbscc{at}ccvax.sinica.edu.tw.
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↵2 W.-Y. Tsai, C.-H. Chen, and S.-C. Cheng, unpublished results.
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↵3 H.-R. Chen, T. Y. Tsao, and S.-C. Cheng, manuscript in preparation.
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↵4 W.-Y. Tsai and S.-C. Cheng, unpublished data.
- Abbreviations:
- kb
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kilobase pair(s)
- ORF
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open reading frame
- BD
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binding domain
- AD
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activation domain
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- Received November 17, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
