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          Institute: MPI für Biochemie     Collection: Structural Biology (W. Baumeister)     Display Documents



ID: 318307.0, MPI für Biochemie / Structural Biology (W. Baumeister)
Automated electron tomography of large nuclear rnp (inrnp) particles - the naturally assembled complexes of precursor messenger rna and splicing factors
Authors:Medalia, O.; Koster, A. J.; Tocilij, A.; Angenitzki, M.; Sperling, J.; Berkovitchyellin, Z.; Sperling, R.
Date of Publication (YYYY-MM-DD):1997-12
Title of Journal:Journal of Structural Biology
Volume:120
Issue / Number:3
Start Page:228
End Page:236
Audience:Not Specified
Abstract / Description:Splicing of nuclear pre-mRNA is an important step in the regulation of gene expression as only correctly spliced mRNAs will be exported to the cytoplasm to function in protein synthesis, Nuclear RNA transcripts of split genes and their splicing products, as well as the general population of nuclear polyadenylated RNA, ape packaged in multicomponent large nuclear ribonucleoprotein (lnRNP) particles. These InRNP particles, which sediment at the 200S region in sucrose gradients, contain all U snRNPs required for pre-mRNA splicing and several protein splicing factors, including U2AF and the SR proteins and can thus be viewed as naturally assembled complexes of pre-mRNA and splicing factors, We have previously reconstructed. the three-dimensional image of negatively stained individual lnRNP particles by automated electron tomography. The reconstruction revealed a compact structure, 50 nm in diameter, composed of four major subunits, Here we further analyzed the reconstructed models and the apparent connectivity between the subunits using anew rendering technique, The uniformity of the lnRNP particles was substantiated by measurement of the volume engulfed by their surface, This study further supports the model proposed for the packaging of nuclear pre-mRNAs in lnRNP particles, where each substructure represents a functional unit. This model is compatible with the requirements for alternative splicing in multiintronic pre-mRNAs, and with the fact that the splicing of multiintronic pre-mRNAs does not occur in a sequential manner. (C) 1997 Academic Press. [References: 50]
Free Keywords:Pre-mrna splicing; Inrnp particles; Model; Electron microscopy; Electron tomography.; Ribonucleoprotein-particles; Conserved family; 3-dimensional reconstruction; Sr proteins; Tilt series; Microscopy; Phosphoproteins; Visualization; Micrographs; Spliceosome.; Biochemistry & biophysics.
External Publication Status:published
Document Type:Article
Communicated by:Anton Hillebrand
Affiliations:MPI für Biochemie/Structural Biology (W. Baumeister)/
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