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Updated: Aug 10, 2026

Single-molecule Super-resolution Imaging of Phosphatidylinositol 4,5-bisphosphate in the Plasma Membrane with Novel Fluorescent Probes
Published on: October 15, 2016
A G-protein beta gamma-subunit-responsive phosphoinositide 3-kinase activity in human platelet cytosol
P A Thomason1, S R James, P J Casey
1Biochemistry Department, University of Dundee, Scotland, United Kingdom.
Abstract:
Thrombin activates phosphoinositide 3-kinase (PI 3-kinase) in platelets via a mechanism involving G-proteins, possibly of both the heterotrimeric and the low molecular weight families. We have investigated the regulation of PI 3-kinase present in platelet cytosol, and we show that this activity can be stimulated by a mixed preparation of G-protein beta gamma-subunits. This stimulation is reversed by preincubation of the beta gamma-subunits with GDP-liganded alpha-subunits. The beta gamma-stimulated activity is inhibited by wortmannin, a recently identified inhibitor of PI 3-kinase in other systems. In addition, the activity associates with PDGF receptor phosphotyrosyl peptide and monoclonal antibody designed to interact with the p85 subunit of PI 3-kinase. We suggest that this beta gamma-sensitive activity is related to previously identified forms of PI 3-kinase.
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