Differential Regulation of Lipid and Protein Kinase Activities of Phosphoinositide 3-Kinase γ in Vitro
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Andrey Bondev
Abstract
G protein sensitive phosphoinositide 3-kinase γ(PI3Kγ) has been characterised as a pleiotropic signalling protein expressing lipid kinase and protein kinase activities. Whereas the regulation of the lipid kinase activity has been investigated in detail, the regulatory features of PI3Kγ protein kinase activity are unknown. Here we report that Gβγ subunits of heterotrimeric G proteins induce a biphasic response of PI3Kγ autophosphorylation in vitro, which contrasts the regulatory effects of the G proteins on PI3Kγ lipid kinase activity. In addition to autophosphorylation PI3Kγ is able to catalyse transphosphorylation of the adapter protein p101 and the protein kinase MEK-1. In the presence of the p101, Gβγ affects PI3Kγ protein kinase activities in a complex manner. In summary, the differential regulatory effects of heterotrimeric G proteins on PI3Kγ lipid and protein kinase activities in vitro reflect the functional diversity of the enzyme observed in vivo.
Copyright © 1999 by Walter de Gruyter GmbH & Co. KG
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Articles in the same Issue
- Secretory Immunoglobulin A: from Mucosal Protection to Vaccine Development
- Cloning of karyopherin-α3 from Drosophila Through Its Interaction with the Nuclear Localization Sequence of Germ Cell-Less Protein
- Regulation of Bile Salt Export Pump mRNA Levels by Dexamethasone and Osmolarity in Cultured Rat Hepatocytes
- High Activity of the Calcineurin A Subunit with a V314 Deletion
- Synthesis, Cytotoxicity and Antitumor Activity of Platinum(II) Complexes of Cyclopentanecarboxylic Acid Hydrazide
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- Mass Spectrometric Characterisation of Post-Translational Modification and Genetic Variation in Human Tetranectin
- Complete Amino Acid Sequence Determination of the Major Allergen of Peach (Prunus persica) Pru p1
- Identification of Immunoreactive Tissue Prokallikrein on the Surface Membrane of Human Neutrophils
- An Evaluation of Techniques for the Extraction and Amplification of DNA from Naturally Shed Hairs
- Isolation of Two Novel Alternative Splicing Variants of Allograft Inflammatory Factor-1
- Differential Regulation of Lipid and Protein Kinase Activities of Phosphoinositide 3-Kinase γ in Vitro
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