Molecular determinants of PI3Kγ-mediated activation downstream of G-protein-coupled receptors (GPCRs)

Oscar Vadas, Hashem A. Dbouk, Aliaksei Shymanets, Olga Perisic, John E. Burke, Widian F.Abi Saab, Bassem D. Khalil, Christian Harteneck, Anne R. Bresnick, Bernd Nürnberg, Jonathan M. Backer, Roger L. Williams

Research output: Contribution to journalArticlepeer-review

96 Scopus citations


Phosphoinositide 3-kinase gamma (PI3Kγ) has profound roles downstream of G-protein-coupled receptors in inflammation, cardiac function, and tumor progression. To gain insight into how the enzyme's activity is shaped by association with its p101 adaptor subunit, lipid membranes, and Gβγ heterodimers, we mapped these regulatory interactions using hydrogen-deuterium exchange mass spectrometry. We identify residues in both the p110γ and p101 subunits that contribute critical interactions with Gβγ heterodimers, leading to PI3Kγ activation. Mutating Gβγ- interaction sites of either p110γ or p101 ablates G-protein-coupled receptor-mediated signaling to p110γ/p101 in cells and severely affects chemotaxis and cell transformation induced by PI3Kγ overexpression. Hydrogen-deuterium exchange mass spectrometry shows that association with the p101 regulatory subunit causes substantial protection of the RBD-C2 linker as well as the helical domain of p110γ. Lipid interaction massively exposes that same helical site, which is then stabilized by Gβγ. Membrane-elicited conformational change of the helical domain could help prepare the enzyme for Gβγ binding. Our studies and others identify the helical domain of the class I PI3Ks as a hub for diverse regulatory interactions that include the p101, p87 (also known as p84), and p85 adaptor subunits; Rab5 and Gβγ heterodimers; and the β-adrenergic receptor kinase.

Original languageEnglish (US)
Pages (from-to)18862-18867
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number47
StatePublished - Nov 19 2013

ASJC Scopus subject areas

  • General


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