Measure of the activation of the rhodopsin promoter by WT and mutant NRL proteins in the presence of CRX with transient transfection assays. DNA constructs encoding WT NRL, NRL-S50T, NRL-P51S, and NRL-L160P proteins were transfected into HEK-293 cells at increasing concentrations (0.0033, 0.01, 0.03, and 0.09 μg) in the presence of a constant amount of pcDNA4-CRX. Fold change is relative to the empty expression vector control. Error bars indicate the SE. SEs for the NRL, S50T, P51S, and L160P samples ranged from 0.17 to 2.75, 0.72 to 1.32, 0.52 to 2.06, and 0.17 to 0.44, respectively.