Composition and three-dimensional EM structure of double affinity-purified, human prespliceosomal A complexes |
| |
Authors: | Behzadnia Nastaran Golas Monika M Hartmuth Klaus Sander Bjoern Kastner Berthold Deckert Jochen Dube Prakash Will Cindy L Urlaub Henning Stark Holger Lührmann Reinhard |
| |
Institution: | Department of Cellular Biochemistry, MPI of Biophysical Chemistry, G?ttingen, Germany. |
| |
Abstract: | Little is known about the higher-order structure of prespliceosomal A complexes, in which pairing of the pre-mRNA's splice sites occurs. Here, human A complexes were isolated under physiological conditions by double-affinity selection. Purified complexes contained stoichiometric amounts of U1, U2 and pre-mRNA, and crosslinking studies indicated that these form concomitant base pairing interactions with one another. A complexes contained nearly all U1 and U2 proteins plus approximately 50 non-snRNP proteins. Unexpectedly, proteins of the hPrp19/CDC5 complex were also detected, even when A complexes were formed in the absence of U4/U6 snRNPs, demonstrating that they associate independent of the tri-snRNP. Double-affinity purification yielded structurally homogeneous A complexes as evidenced by electron microscopy, and allowed for the first time the generation of a three-dimensional structure. A complexes possess an asymmetric shape (approximately 260 x 200 x 195 angstroms) and contain a main body with various protruding elements, including a head-like domain and foot-like protrusions. Complexes isolated here are well suited for in vitro assembly studies to determine factor requirements for the A to B complex transition. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|