The effects of varying RK (GRK1) expression on the photoresponse, as carried out by Sakurai et al. (ref. . (A′-D′) Simulations of the same experiments. A′) Normalized responses to a non-saturating flash (135 R*). 0.3x RK underexpression (dotted-dashed traces) leads to a slowed normalized recovery to a non-stimulating flash, while recovery is slightly accelerated for 3x RK overexpression (dashed traces). B′) The time constant of recovery, τrec, as a function of RK expression. C′) Typical Pepperberg plots (ref. ) reporting the saturation time, Tsat, as a function of stimulus intensity (in log units; WT: circles; 0.3x RK underexpression: squares; 3x RK overexpression: stars). 0.3x RK underexpression results in higher than normal Tsat values for saturating flashes. 3x RK overexpression, on the other hand, results in a slight decrease in Tsat. D′) The dominant time constant of recovery from saturating flashes, τD, is not affected by RK expression levels. (Panels A-D copyright © 2011 The Association for Research in Vision and Ophthalmology, Inc.). NB: the authors used “Grk1” and “GRK1” interchangeably, and used “GRK1+” to indicate overexpression instead of the more common “GRK1+/+”).