Differential effects on Rap1 activation in Gαi₂^−/− murine platelets in response to ADP and CVX.

(A) Washed wild-type (wt) and Gαi₂-deficient murine platelets were stimulated with 50 μM ADP or 500 ng/mL CVX for 1 minute before lysis. GTP-bound Rap1 was precipitated and detected as described in Figure 1, except that a polyclonal antibody was used to detect Rap1. Relative quantities of active Rap1 were determined via densitometry and normalized to levels of active Rap1 in unstimulated platelets on the same blot. The wild-type and Gαi₂^−/− murine platelet results are plotted as an average fold of Rap1 activation ± SEM (n = 6). (B) In a representative blot the GTP-Rap1 bands in the control (Cont) lanes are assigned a fold Rap1 activation value of 1.0, indicated by the dashed line in the histogram.