A G-protein beta gamma-subunit-responsive phosphoinositide 3-kinase activity in human platelet cytosol.
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.
Duke Scholars
Published In
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Wortmannin
- Receptors, Platelet-Derived Growth Factor
- Phosphotransferases (Alcohol Group Acceptor)
- Phosphopeptides
- Phosphatidylinositol 3-Kinases
- Peptide Fragments
- Macromolecular Substances
- Kinetics
- Humans
- Guanosine 5'-O-(3-Thiotriphosphate)
Citation
Published In
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Wortmannin
- Receptors, Platelet-Derived Growth Factor
- Phosphotransferases (Alcohol Group Acceptor)
- Phosphopeptides
- Phosphatidylinositol 3-Kinases
- Peptide Fragments
- Macromolecular Substances
- Kinetics
- Humans
- Guanosine 5'-O-(3-Thiotriphosphate)