Fig. 5. P2Y₂R-v integrin interaction is required for G₁₂ coupling. (A,B) Membrane preparations from 1321N1 cells expressing the WT or RGE mutant P2Y₂R or pLXSN vector-transfected cells (negative control) were used in [³⁵S]GTPS binding assays in the presence or absence of 1 mM UTP. After termination of the assay, samples were immunoprecipitated with antiserum against (A) G₁₂ or (B) G_q/11 and radioactivity in the immunoprecipitates was calculated. Data are the means ± s.e.m. of results from three separate experiments and are shown as fold increase over untreated cells. (C) Human 1321N1 cells expressing the WT or RGE mutant P2Y₂R were incubated with 1 mM UTP for 2 minutes. G₁₂ activation was detected by immunoprecipitation (IP) of G₁₂ with anti-G₁₂ antibody and immunoblotting (IB) of G₁₂ with anti-phosphoserine/threonine antibody. G_q/11 activation was detected by IP with anti-phosphotyrosine antibody and IB with anti-G_q/11 antibody. Blots representative of three experiments are shown.