Related Experiment Video
Updated: Jul 18, 2026
13:00
A Rapid High-throughput Method for Mapping Ribonucleoproteins (RNPs) on Human pre-mRNA
Published on: December 2, 2009
Assembly and transport of a premessenger RNP particle
1Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institutet, Box 285, SE-17177 Stockholm, Sweden. Bertil.Daneholt@cmb.ki.se
Summary
The study visualizes the assembly and transport of salivary polypeptide transcripts in Chironomus tentans larvae. Proteins are added during transcription, influencing mRNA fate even at the gene level.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Chironomus tentans salivary gland cells provide a model for studying gene expression and nucleocytoplasmic transport.
- Giant polytene chromosomes with large transcriptionally active 'puffs', specifically Balbiani rings (BR), facilitate visualization.
- BR genes encode large salivary polypeptides, and their transcripts form ribonucleoprotein (RNP) particles.
Purpose of the Study:
- To visualize the assembly and nucleocytoplasmic transport of specific transcription products.
- To elucidate the role of proteins in the formation and transport of BR RNP particles.
- To understand how cotranscriptional assembly influences mRNA fate.
Main Methods:
- Observation of salivary gland cells in Chironomus tentans larvae.
- Analysis of transcription sites on giant polytene chromosomes (Balbiani rings).
- Characterization of proteins involved in pre-mRNA processing and RNP particle formation.
Main Results:
- The assembly of BR transcripts into RNP fibrils and their transport through the nuclear pore were visualized.
- Proteins are added cotranscriptionally to the pre-mRNA, influencing RNP particle structure and transport.
- Different proteins exhibit distinct behaviors during RNA transport, linked to their specific functions.
Conclusions:
- The fate of mRNA is significantly determined at the gene level through cotranscriptional assembly.
- Nucleocytoplasmic transport involves dynamic unfolding and processing of RNP particles.
- Understanding RNP biogenesis provides insights into gene expression regulation.
More Related Videos
Related Concept Videos
02:31Nuclear Export of mRNA
Before mRNAs are exported to the cytoplasm, it is crucial to check each mRNA for structural and functional integrity. Eukaryotic cells use several different mechanisms, collectively known as mRNA surveillance, to look for irregularities in mRNAs. Irregular or aberrant mRNA are rapidly degraded by various enzymes. If a defective mRNA escapes the surveillance, it would be translated into a protein which would either be non-functional or not function properly. One of the primary irregularities in...
02:53Ribosomal RNA Synthesis
Ribosome synthesis is a highly complex and coordinated process involving more than 200 assembly factors. The synthesis and processing of ribosomal components occurs not only in the nucleolus but also in the nucleoplasm and the cytoplasm of eukaryotic cells.
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...
02:22Regulated mRNA Transport
In eukaryotes, transcription and translation are compartmentalized; an mRNA is first synthesized in the nucleus and then selectively transported to the cytoplasm for protein synthesis. Before transport, a pre-mRNA undergoes several steps of post-transcriptional modifications including splicing, 5' capping, and the addition of a poly-adenine tail. Various proteins bind to the pre-mRNA during these modifications. The mRNA transport takes place with the help of multiple proteins playing specific...
01:34Nuclear Protein Sorting
Nuclear protein sorting is the selective trafficking of histones, polymerases, gene regulatory proteins into the nucleus and exporting RNAs and ribosomes to the cytosol. It is a tightly controlled process that regulates gene expression within a cell.
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
01:34Directing Proteins to the Rough Endoplasmic Reticulum
The organelle-specific signaling sequences direct proteins synthesized in the cytosol to their final destination like ER, mitochondria, peroxisomes, etc. Some of the proteins directed to ER are then trafficked via vesicles to other organelles within the cell or the extracellular environment through the Golgi complex. For example, the rough ER synthesizes soluble proteins for transportation to the lysosomes or secretion out of the cell. It can also synthesize transmembrane proteins that can...
01:27Post-translational Translocation of Proteins to the RER
A sizable fraction of proteins destined for ER are first synthesized in the cell cytosol and then transported across the ER membrane–a process called post-translational translocation. Similar to cotranslationally translocated proteins, these proteins also use the Sec translocon complex to enter the ER lumen.
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...