What question did this study set out to answer?

To purify and characterize the G-protein βγ subunit-responsive phosphoinositide 3-kinase from pig platelet cytosol and define its enzymatic and regulatory properties.

May 1, 1997Journal of Biological ChemistryOpen Access

Purification and Characterization of Gβγ-responsive Phosphoinositide 3-Kinases from Pig Platelet Cytosol

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Authors

XTXiuwen TangZhejiang International Studies University CDC. Peter DownesUniversity of Dundee

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Implication

Biochemical analysis uncovers distinct Gβγ-activated phosphoinositide 3-kinase kinetics in porcine platelet cytosol, highlighting cooperative activation mechanisms across signaling pathways.

Key Points

To purify and characterize the G-protein βγ subunit-responsive phosphoinositide 3-kinase from pig platelet cytosol and define its enzymatic and regulatory properties.
Purified PI 3-kinase approximately 5000-fold from pig platelet cytosol using polyethylene glycol precipitation followed by sequential column chromatography on Q-Sepharose, gel filtration, heparin-Sepharose, and hydroxyapatite.
Assayed substrate kinetics for ATP and lipid substrates (PtdIns, PtdIns4P, and PtdIns(4,5)P2) under basal conditions and in the presence of Gβγ subunits, alongside inhibition testing with wortmannin and LY294002.
The purified 210 kDa enzyme cross-reacted with anti-p110γ antibodies and responded to Gβγ subunits by increasing Vmax 2-fold with PtdIns, 3.5-fold with PtdIns4P, and 10-fold with PtdIns(4,5)P2, without altering ATP Km values.
Enzyme activity was inhibited by wortmannin and LY294002 with IC50 values of 10 nM and 2 µM, respectively.
Unlike p85-associated PI 3-kinase, the p110γ-related enzyme was not activated by Gαi/o subunits and did not associate with a PtdIns(3,4,5)P3-specific 5-phosphatase.

Cite This Study

Tang et al. (1997) studied this question.

synapsesocial.com/papers/6a7ea574cb17bc2d1d0d242b https://doi.org/10.1074/jbc.272.22.14193

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Implication

Biochemical analysis uncovers distinct Gβγ-activated phosphoinositide 3-kinase kinetics in porcine platelet cytosol, highlighting cooperative activation mechanisms across signaling pathways.

Purification and Characterization of Gβγ-responsive Phosphoinositide 3-Kinases from Pig Platelet Cytosol

Discussion

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Implication

Key Points

Cite This Study

Purification and Characterization of Gβγ-responsive Phosphoinositide 3-Kinases from Pig Platelet Cytosol

Discussion

Member takes

Implication

Key Points

Cite This Study

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