The heterotrimeric G protein Gβ1 interacts with the catalytic subunit of protein phosphatase 1 and modulates G protein–coupled receptor signaling in platelets

• DOI: 10.1074/jbc.m117.796656
• Publication Date: 2017-06-15T00:40:15Z
• Authors: Subhashree Pradhan; Tanvir Khatlani; Angus C. Nairn; K. Vinod Vijayan
• Keywords: G beta-gamma complex; Protein phosphatase 1

Thrombosis is caused by the activation of platelets at site ruptured atherosclerotic plaques. This involves engagement G protein–coupled receptors (GPCR) on that promote their aggregation. Although it known protein kinases and phosphatases modulate GPCR signaling, how serine/threonine integrate with signaling pathways less understood. Because subcellular localization substrate specificity catalytic subunit phosphatase 1 (PP1c) dictated PP1c-interacting proteins, here we sought to identify new PP1c interactors. GPCRs signal via canonical heterotrimeric Gα Gβγ subunits. Using a yeast two-hybrid screen, discovered an interaction between PP1cα Gβ1 subunit. Co-immunoprecipitation studies epitope-tagged revealed interacts α, β, γ1 isoforms. Purified bound recombinant Gβ1-GST protein, co-immunoprecipitated in unstimulated platelets. Thrombin stimulation induced dissociation PP1c-Gβ1 complex, which correlated association phospholipase C β3 (PLCβ3), along concomitant dephosphorylation inhibitory Ser1105 residue PLCβ3. siRNA-mediated depletion GNB1 (encoding Gβ1) murine megakaryocytes reduced protease-activated receptor 4, activating peptide-induced soluble fibrinogen binding. Thrombin-induced aggregation was decreased PP1cα−/− human treated small-molecule inhibitor Gβγ. Finally, disruption complexes myristoylated peptides containing binding moderately thrombin-induced platelet These findings suggest enlists