Figure 2.
Effect of Gt-derived peptides on photoregeneration from metarhodopsin II. Gt-derived peptides, Gtα(340–350) high-affinity analog (A) and Gtγ(50–71)farnesyl (B) block photoregeneration from the bound state in a concentration-dependent manner. Blockage is more effective at pH 8 (Lower) than at pH 6 (Upper). At pH 6, Gtα(340–350) high-affinity analog shows a concentration-dependent complex dissociation and reversion to the dark form. Under these measuring conditions, ca. 15% of the signal amplitude is caused by the fast formation of an additional photoproduct, which is not affected by ligand binding (20) (vertical scale bars are 8·10−5 (A) and 2·10−4 (B) absorption units).