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Modulation of phosphorylation of a 30-kD polyribosomal protein (pp30) by ACTH and spermine: comparison with

L H Schrama, H Frankena, P M Edwards

    Journal of Neurochemistry
    |December 1, 1984
    PubMed

    Insights

    Adrenocorticotropin (ACTH) and spermine modulate brain protein phosphorylation, specifically a 30-kD phosphoprotein (pp30). This modulation may relate to brain cell-free protein synthesis, with ACTH fragments showing inhibitory activity.

    Area of Science:

    • Neurochemistry
    • Molecular Biology
    • Protein Phosphorylation

    Background:

    • Brain protein phosphorylation plays a role in cellular signaling and function.
    • Adrenocorticotropin (ACTH) and polyamines like spermine are known to influence neuronal processes.

    Purpose of the Study:

    • To investigate the effects of ACTH and spermine on protein phosphorylation in brain extracts.
    • To identify specific proteins modulated by these agents and explore their functional significance.

    Main Methods:

    • Gel electrophoresis was used to separate and identify phosphorylated proteins in brain postmitochondrial supernatant and free polyribosomal fractions.
    • Phosphorylation assays were conducted in the presence of varying concentrations of spermine, ACTH, and Mg2+.
    • Structure-activity relationship studies were performed using ACTH fragments and polylysine.

    Main Results:

    • A specific 30-kD phosphoprotein (pp30) was identified, whose phosphorylation was modulated by spermine and ACTH.
    • The enzyme activity for pp30 phosphorylation and its sensitivity to spermine and ACTH were retained in the free polyribosomal fraction.
    • ACTH(11-24) and other ACTH fragments, as well as polylysine fragments, exhibited inhibitory effects on pp30 phosphorylation.

    Conclusions:

    • pp30 phosphorylation is sensitive to ACTH and spermine, suggesting a role in neuronal signaling.
    • The findings suggest a potential link between pp30 phosphorylation modulation and brain cell-free protein synthesis regulation.
    • Further research is warranted to elucidate the precise mechanisms and physiological relevance of these interactions.

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