Figure 4.

GTPase accelerating activity of RET-RGS-d on transducin. (A) Kinetics of GTP hydrolysis by transducin reconstituted with bleached urea-stripped ROS membranes in the absence (○) or presence (•) of 5 μM RET-RGS-d. (B) Titration of the GAP activity of RET-RGS-d (•), using his-tagged neurocalcin (□) and BSA (▵) as controls. The rate of hydrolysis of GTP by Tα was measured at 5 μM final concentration of bleached urea-stripped ROS membranes and 400 nM final concentration of transducin, concentrations that we determined to be saturating under these conditions. These experiments were repeated three times with similar results.