Related Experiment Video

Updated: Jul 17, 2026

Polysome Fractionation and Analysis of Mammalian Translatomes on a Genome-wide Scale
10:56

Polysome Fractionation and Analysis of Mammalian Translatomes on a Genome-wide Scale

Published on: May 17, 2014

Regulation of mRNA entry into polysomes. Parameters affecting polysome size and the fraction of mRNA in polysomes

E M Nelson, M M Winkler

    The Journal of Biological Chemistry
    |August 25, 1987
    PubMed

    Insights

    Histone mRNA rapidly binds ribosomes, but large polysome formation takes time. Initiation and reinitiation rates may differ, suggesting complex control over polysome size and mRNA translation.

    Area of Science:

    • Molecular Biology
    • Biochemistry
    • Gene Expression Regulation

    Background:

    • Polysomes are essential for protein synthesis, translating messenger RNA (mRNA) into proteins.
    • Understanding the kinetics of mRNA incorporation into polysomes is crucial for elucidating gene expression regulation.

    Purpose of the Study:

    • To investigate the kinetics of labeled histone mRNA entry into polysomes.
    • To explore the factors influencing polysome size and mRNA translation efficiency.

    Main Methods:

    • Utilized nuclease-treated reticulocyte lysates for studying mRNA-polysome interactions.
    • Employed labeled histone mRNA to track its entry into polysomes.
    • Administered initiation inhibitors (aurintricarboxylic acid, 7-methylguanosine 5'-triphosphate) to assess their effects.

    Main Results:

    • Histone mRNA rapidly bound 1-2 ribosomes, but full polysome formation required at least 16 minutes.
    • Maximum mRNA binding to ribosomes (73%) occurred within 2 minutes, followed by a slow decline.
    • Initiation inhibitors differentially affected polysome size and mRNA fraction, suggesting distinct initiation and reinitiation mechanisms.

    Conclusions:

    • Histone mRNA translation involves complex kinetics with distinct phases of ribosome binding and polysome assembly.
    • Initiation and reinitiation events in translation may be intrinsically different processes.
    • Multiple regulatory levels likely control polysome size and the proportion of mRNA engaged in translation.

    More Related Videos

    Assessment of Selective mRNA Translation in Mammalian Cells by Polysome Profiling10:00

    Assessment of Selective mRNA Translation in Mammalian Cells by Polysome Profiling

    Published on: October 28, 2014

    Polysome Profiling in Leishmania, Human Cells and Mouse Testis14:32

    Polysome Profiling in Leishmania, Human Cells and Mouse Testis

    Published on: April 8, 2018

    Related Concept Videos

    Chromatin Structure Regulates pre-mRNA Processing02:41

    Chromatin Structure Regulates pre-mRNA Processing

    In eukaryotic cells, nascent mRNA transcripts need to undergo many post-transcriptional modifications to reach the cell cytoplasm and translate into functional proteins. For a long time, transcription and pre-mRNA processing were considered two independent events that occur sequentially in the cell. However, it has now been well established that transcription and pre-mRNA processing are two simultaneous processes that are precisely regulated inside the cell.
    The chromatin structure, especially...
    Regulation of Expression Occurs at Multiple Steps02:24

    Regulation of Expression Occurs at Multiple Steps

    Gene expression can be regulated at almost every step from gene to protein. Transcription is the step that is most commonly regulated. This involves the binding of proteins to short regulatory sequences on the DNA. This association can either promote or inhibit the transcription of a gene associated with the respective sequence.
    Transcription results in the generation of precursor (pre-mRNA) that consists of both exons and introns, which needs further processing before being translated to a...
    Regulated mRNA Transport02:22

    Regulated 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...
    Regulated mRNA Transport02:22

    Regulated 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...
    Regulation of Expression at Multiple Steps01:23

    Regulation of Expression at Multiple Steps

    The gene expression in cells is regulated at different stages: (i) transcription, (ii) RNA processing, (iii) RNA localization, and (iv) translation. Transcriptional regulation is mediated by regulatory proteins such as transcription factors, activators, or repressors—these control gene expression by initiating or inhibiting the transcription of genes. Once a precursor or pre-mRNA is produced, it undergoes post-transcriptional modification, including 5' capping, splicing, and the addition of a...
    Translational Regulation01:29

    Translational Regulation

    Translational regulation in prokaryotes ensures efficient protein synthesis by controlling ribosome access to mRNA. This regulation is mediated by secondary RNA structures, including translational riboswitches, RNA thermometers, and small RNAs (sRNAs), which respond to intracellular and environmental signals to modulate gene expression.Translational RiboswitchesRiboswitches in the leader region of mRNAs can regulate translation by altering the accessibility of the Shine-Dalgarno (SD) sequence,...