Radiolabeling of Catalytic Subunits of PI 3-Kinases with 17β-Hydroxy-16α-(125I)Iodowortmannin

Identification of the Gβγ-Sensitive Isoform as a Complex Composed of 45- and 100-kDa Subunits

H. Kurosu, O. Hazeki, I. Kukimoto, S. Honzawa, M. Shibasaki, Masahisa Nakada, M. Ui, T. Katada

    Research output: Contribution to journalArticle

    12 Citations (Scopus)

    Abstract

    A fungal metabolite, wortmannin, is a potent inhibitor of phosphatidylinositol (PI) 3-kinases. In the present study, we prepared a radio-labeled derivative of wortmannin, 17β-hydroxy-16α-[125I] iodowortmannin. The compound bound tightly to a 110-kDa subunit in the previously identified isoform of PI 3-kinase (p85/p110), and also to a 100-kDa peptide in a partially purified preparation of another isoform of PI 3-kinase whose activity was markedly stimulated by the βγ subunits of GTP-binding proteins (Gβγ). The binding to both peptides was inhibited by non-radiolabeled wortmannin and also by LY294002, another inhibitor of PI 3-kinases. An antibody against p85 recognized a 46-kDa peptide in the Gβγ-sensitive isozyme and precipitated the 100-kDa peptide specifically labeled with 17β-hydroxy-16α-[125I] iodowortmannin. These results suggested that the newly found isozyme was a complex composed of 46-kDa and 100-kDa peptides.

    Original languageEnglish
    Pages (from-to)655-661
    Number of pages7
    JournalBiochemical and Biophysical Research Communications
    Volume216
    Issue number2
    DOIs
    Publication statusPublished - 1995 Nov 13

    Fingerprint

    Phosphatidylinositol 3-Kinases
    Catalytic Domain
    Protein Isoforms
    Peptides
    Phosphatidylinositol 3-Kinase
    Isoenzymes
    2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
    Metabolites
    Radio
    GTP-Binding Proteins
    17-hydroxy-16-iodowortmannin
    Derivatives
    Antibodies
    wortmannin

    ASJC Scopus subject areas

    • Molecular Biology
    • Cell Biology
    • Biophysics
    • Biochemistry

    Cite this

    Radiolabeling of Catalytic Subunits of PI 3-Kinases with 17β-Hydroxy-16α-(125I)Iodowortmannin : Identification of the Gβγ-Sensitive Isoform as a Complex Composed of 45- and 100-kDa Subunits. / Kurosu, H.; Hazeki, O.; Kukimoto, I.; Honzawa, S.; Shibasaki, M.; Nakada, Masahisa; Ui, M.; Katada, T.

    In: Biochemical and Biophysical Research Communications, Vol. 216, No. 2, 13.11.1995, p. 655-661.

    Research output: Contribution to journalArticle

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