Figure 7.

Cone arrestin is less efficient than rod arrestin at inactivating transgenic S-pigment, expressed in rods. A, Normalized dim-flash responses from transgenic S-pigment in control rod (S-opsin^rho−/−, black), rod lacking rod arrestin (S-opsin^{rho−/−arr1−/−}, red), and rod lacking rod arrestin but expressing cone arrestin (S-opsin^rho−/− MCAR-H^arr1−/−, blue). Deletion of rod arrestin results in slower recovery of the dim-flash response, which is not reversed by the transgenic expression of cone arrestin. B, Family of flash responses from S-opsin^rho−/− MCAR-H^arr1−/− rod. Cone arrestin partially reverses the slow decay of the responses to brighter flashes (compare with Fig. 6C). C, Comparison of normalized dim-flash responses from S-opsin^{rho−/−arr1−/−} rod (red) and arr1−/− cone (blue), with recovery fit by a single exponential decay function (black) in each case. The cone-response recovery is significantly faster than the decay of S-opsin meta II, which is rate limiting for the recovery of the rod.