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Eukaryotic Polyribosome Profile Analysis
09:16

Eukaryotic Polyribosome Profile Analysis

Published on: June 16, 2010

Characterization of the poly(ADP-ribose) polymerase associated with free cytoplasmic mRNA-protein particles

H Thomassin, C Niedergang, P Mandel

    Biochemical and Biophysical Research Communications
    |December 17, 1985
    PubMed

    Insights

    Free cytoplasmic poly(ADP-ribose) polymerase (PARP) in messenger ribonucleoprotein particles (mRNP) is DNA-independent and can be activated by RNA degradation or high salt concentrations. This enzyme may play a role in post-translational modification of mRNP proteins for mRNA translation.

    Area of Science:

    • Molecular Biology
    • Biochemistry
    • Cell Biology

    Background:

    • Poly(ADP-ribose) polymerase (PARP) is a key nuclear enzyme involved in DNA repair.
    • The presence and function of PARP in the cytoplasm, particularly associated with messenger ribonucleoprotein particles (mRNP), are less understood.

    Purpose of the Study:

    • To characterize the properties of cytoplasmic PARP associated with free mRNP particles.
    • To investigate the relationship between cytoplasmic PARP and mRNP structure and function.

    Main Methods:

    • Enzymatic assays to measure PARP activity.
    • Biochemical techniques including high salt extraction and RNase A treatment.
    • Immunological methods to compare cytoplasmic and nuclear PARP.

    Main Results:

    • Cytoplasmic PARP was found to be associated with free mRNP particles in mouse plasmacytoma.
    • This enzyme is DNA-independent, shares antigenic sites with nuclear PARP, and undergoes auto-ADP-ribosylation.
    • PARP activity was enhanced upon release from mRNP by high salt (0.7 M KCl) or by RNase A treatment, suggesting RNA interaction.
    • mRNP structural changes, induced by salt or RNase, exposed new protein sites for ADP-ribosylation.

    Conclusions:

    • Cytoplasmic PARP is a distinct enzyme associated with mRNP particles.
    • Its activity is modulated by mRNP structure and RNA content.
    • Poly(ADP-ribosylation) may serve as a post-synthetic modification regulating mRNP protein function and mRNA translation.

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