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Association of phosphatidylinositol kinase activity with polyoma middle-T competent for transformation

M Whitman, D R Kaplan, B Schaffhausen

    Nature
    |May 16, 1985
    PubMed

    Insights

    Polyoma middle-T antigen

    Area of Science:

    • Molecular Biology
    • Virology
    • Cellular Biology

    Background:

    • Polyoma middle-T antigen is crucial for viral transformation and animal tumorigenesis.
    • Middle-T antigen exhibits membrane-bound tyrosine kinase activity, interacting with cellular pp60c-src.
    • Viral transforming proteins like pp60v-src and pp68v-ros show phosphatidylinositol (PI) kinase activity, impacting PI turnover.

    Purpose of the Study:

    • To investigate the association between polyoma middle-T antigen and phosphatidylinositol (PI) kinase activity.
    • To determine if PI kinase activity is linked to the transforming capabilities of middle-T antigen.

    Main Methods:

    • Immunoprecipitation assays using antisera specific to middle-T antigen or pp60c-src in polyoma virus-infected cells.
    • Assaying immunoprecipitates for associated phosphatidylinositol (PI) kinase activity.
    • Analyzing PI kinase activity in middle-T mutants with varying transformation efficiencies.

    Main Results:

    • Phosphatidylinositol (PI) kinase activity was detected in immunoprecipitates containing polyoma middle-T antigen.
    • A strong correlation was observed between PI kinase activity and the transformation proficiency of middle-T antigen mutants.
    • These findings suggest middle-T antigen directly possesses PI kinase activity.

    Conclusions:

    • Polyoma middle-T antigen possesses associated phosphatidylinositol (PI) kinase activity.
    • This PI kinase activity is closely linked to the viral transformation process mediated by middle-T antigen.
    • The study implicates PI turnover in viral transformation mechanisms.

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