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Title: The transition in spliceosome assembly from complex E to complex A purges surplus U1 snRNPs from alternative splice sites.
Authors: Hodson, Mark J.
Hudson, Andrew J.
Cherny, Dmitry
Eperon, Ian C.
First Published: 13-Apr-2012
Publisher: Oxford University Press
Citation: Nucleic Acids Research, 2012, 40 (14), pp. 6850-6862
Abstract: Spliceosomes are assembled in stages. The first stage forms complex E, which is characterized by the presence of U1 snRNPs base-paired to the 5' splice site, components recognizing the 3' splice site and proteins thought to connect them. The splice sites are held in close proximity and the pre-mRNA is committed to splicing. Despite this, the sites for splicing appear not to be fixed until the next complex (A) forms. We have investigated the reasons why 5' splice sites are not fixed in complex E, using single molecule methods to determine the stoichiometry of U1 snRNPs bound to pre-mRNA with one or two strong 5' splice sites. In complex E most transcripts with two alternative 5' splice sites were bound by two U1 snRNPs. However, the surplus U1 snRNPs were displaced during complex A formation in an ATP-dependent process requiring an intact 3' splice site. This process leaves only one U1 snRNP per complex A, regardless of the number of potential sites. We propose a mechanism for selection of the 5' splice site. Our results show that constitutive splicing components need not be present in a fixed stoichiometry in a splicing complex.
DOI Link: 10.1093/nar/gks322
eISSN: 1362-4962
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © The Author(s) 2012. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Appears in Collections:Published Articles, Dept. of Biochemistry

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