scholarly journals Higher-Order Organization Principles of Pre-translational mRNPs

2018 ◽  
Author(s):  
Mihir Metkar ◽  
Hakan Ozadam ◽  
Bryan R. Lajoie ◽  
Maxim Imakaev ◽  
Leonid A. Mirny ◽  
...  
Keyword(s):  
High Resolution ◽  
Noncoding Rnas ◽  
Eukaryotic Cells ◽  
Exon Junction Complex ◽  
Specific Interactions ◽  
Flexible Polymers ◽  
Tertiary Structures ◽  
Proximity Ligation ◽  
Exon Junction ◽  
Endonuclease Digestion

SummaryCompared to noncoding RNAs (ncRNAs) such as rRNAs and ribozymes, for which high resolution structures abound, little is known about the tertiary structures of mRNAs. In eukaryotic cells, newly made mRNAs are packaged with proteins in highly compacted mRNPs, but the manner of this mRNA compaction is unknown. Here we developed and implemented RIPPLiT (RNA ImmunoPrecipitation and Proximity Ligation in Tandem), a transcriptome-wide method for probing the 3D conformations of RNAs stably-associated with defined proteins, in this case exon junction complex (EJC) core factors. EJCs multimerize with other mRNP components to form megadalton sized complexes that protect large swaths of newly synthesized mRNAs from endonuclease digestion. Unlike ncRNAs, mRNAs behave more like flexible polymers without strong locus-specific interactions. Polymer analysis of proximity ligation data for hundreds of mRNA species demonstrates that pre-translational mammalian mRNPs fold as linear rod-like structures with no strong propensity for 5’ and 3’ end interaction.

High resolution spot scan imaging of frozen, hydrated actin bundles with 400kV electrons

1992 ◽  
Vol 50 (1) ◽  
pp. 512-513
Author(s):  
J. Jakana ◽  
M.F. Schmid ◽  
P. Matsudaira ◽  
W. Chiu
Keyword(s):  
High Resolution ◽  
Binding Proteins ◽  
Actin Binding ◽  
Eukaryotic Cells ◽  
Dimensional Structure ◽  
Structural Basis ◽  
Actin Bundle ◽  
Actin Bundles ◽  
3 Dimensional ◽  
Macromolecular Assembly

Actin is a protein found in all eukaryotic cells. In its polymerized form, the cells use it for motility, cytokinesis and for cytoskeletal support. An example of this latter class is the actin bundle in the acrosomal process from the Limulus sperm. The different functions actin performs seem to arise from its interaction with the actin binding proteins. A 3-dimensional structure of this macromolecular assembly is essential to provide a structural basis for understanding this interaction in relationship to its development and functions.

Structural insights into the exon junction complex

2008 ◽  
Vol 18 (1) ◽  
pp. 112-119 ◽  
Author(s):  
Hervé Le Hir ◽  
Gregers Rom Andersen
Keyword(s):  
Exon Junction Complex ◽  
Exon Junction ◽  
Structural Insights

scholarly journals The Exon Junction Complex Core Represses Cancer-Specific Mature mRNA Re-Splicing: A Potential Key Role in Terminating Splicing

2021 ◽  
Vol 22 (12) ◽  
pp. 6519
Author(s):  
Yuta Otani ◽  
Ken-ichi Fujita ◽  
Toshiki Kameyama ◽  
Akila Mayeda
Keyword(s):  
Cancer Cells ◽  
Control Factor ◽  
Exon Junction Complex ◽  
Core Component ◽  
Normal Cells ◽  
Knock Down ◽  
Exon Junction ◽  
Mature Mrna ◽  
Complex Core ◽  
Specific Mrna

Using TSG101 pre-mRNA, we previously discovered cancer-specific re-splicing of mature mRNA that generates aberrant transcripts/proteins. The fact that mRNA is aberrantly re-spliced in various cancer cells implies there must be an important mechanism to prevent deleterious re-splicing on the spliced mRNA in normal cells. We thus postulated that mRNA re-splicing is controlled by specific repressors, and we searched for repressor candidates by siRNA-based screening for mRNA re-splicing activity. We found that knock-down of EIF4A3, which is a core component of the exon junction complex (EJC), significantly promoted mRNA re-splicing. Remarkably, we could recapitulate cancer-specific mRNA re-splicing in normal cells by knock-down of any of the core EJC proteins, EIF4A3, MAGOH, or RBM8A (Y14), implicating the EJC core as the repressor of mRNA re-splicing often observed in cancer cells. We propose that the EJC core is a critical mRNA quality control factor to prevent over-splicing of mature mRNA.

scholarly journals Functional interconnections of Arabidopsis exon junction complex proteins and genes at multiple steps of gene expression

2011 ◽  
Vol 62 (14) ◽  
pp. 5025-5036 ◽  
Author(s):  
Eduardo F. Mufarrege ◽  
Daniel H. Gonzalez ◽  
Graciela C. Curi
Keyword(s):  
Gene Expression ◽  
Exon Junction Complex ◽  
Exon Junction
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