MCB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Eperon, I. C.
Right arrow Articles by Krainer, A. R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Eperon, I. C.
Right arrow Articles by Krainer, A. R.

Next Article 

Molecular and Cellular Biology, November 2000, p. 8303-8318, Vol. 20, No. 22
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

Selection of Alternative 5' Splice Sites: Role of U1 snRNP and Models for the Antagonistic Effects of SF2/ASF and hnRNP A1

Ian C. Eperon,1,* Olga V. Makarova,1,dagger Akila Mayeda,2,3 Stephen H. Munroe,4 Javier F. Cáceres,2,5 Daniel G. Hayward,1 and Adrian R. Krainer2

Department of Biochemistry, University of Leicester, Leicester LE1 7RH,1 and MRC Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, United Kingdom5; Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724-22082; Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Miami, Florida 33136-10193; and Department of Biology, Marquette University, Milwaukee, Wisconsin 532334

Received 26 May 2000/Returned for modification 13 July 2000/Accepted 24 August 2000

The first component known to recognize and discriminate among potential 5' splice sites (5'SSs) in pre-mRNA is the U1 snRNP. However, the relative levels of U1 snRNP binding to alternative 5'SSs do not necessarily determine the splicing outcome. Strikingly, SF2/ASF, one of the essential SR protein-splicing factors, causes a dose-dependent shift in splicing to a downstream (intron-proximal) site, and yet it increases U1 snRNP binding at upstream and downstream sites simultaneously. We show here that hnRNP A1, which shifts splicing towards an upstream 5'SS, causes reduced U1 snRNP binding at both sites. Nonetheless, the importance of U1 snRNP binding is shown by proportionality between the level of U1 snRNP binding to the downstream site and its use in splicing. With purified components, hnRNP A1 reduces U1 snRNP binding to 5'SSs by binding cooperatively and indiscriminately to the pre-mRNA. Mutations in hnRNP A1 and SF2/ASF show that the opposite effects of the proteins on 5'SS choice are correlated with their effects on U1 snRNP binding. Cross-linking experiments show that SF2/ASF and hnRNP A1 compete to bind pre-mRNA, and we conclude that this competition is the basis of their functional antagonism; SF2/ASF enhances U1 snRNP binding at all 5'SSs, the rise in simultaneous occupancy causing a shift in splicing towards the downstream site, whereas hnRNP A1 interferes with U1 snRNP binding such that 5'SS occupancy is lower and the affinities of U1 snRNP for the individual sites determine the site of splicing.


* Corresponding author. Mailing address: Department of Biochemistry, University of Leicester, Leicester LE1 7RH, United Kingdom. Phone: 44 116 2523482. Fax: 44 116 2523369. E-mail: eci{at}le.ac.uk.

dagger Present address: Max-Planck-Institut fur Biophysikalische Chemie, Abt. Zellulare Biochemie, 37077 Gottingen, Germany.


Molecular and Cellular Biology, November 2000, p. 8303-8318, Vol. 20, No. 22
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.



This article has been cited by other articles:




Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. J. Virol. Eukaryot. Cell
Microbiol. Mol. Biol. Rev. Clin. Vaccine Immunol. All ASM Journals

Copyright © 2000 by the American Society for Microbiology. All rights reserved.