FIGURE 2.

Effect of 11-cis-retinol and -retinal on salamander opsin activation and pigment regeneration in red cones. A, transducin activation by expressed salamander red cone opsin (open circles) with 11-cis-retinol (filled circles) and 11-cis-retinal (triangles). Each sample was assayed in triplicate and averaged; error bars reflect mean ± S.E. and often were smaller than the symbol size. At 5.5 min, samples with 11-cis-retinal and 11-cis-retinol were illuminated with light for 12 s as described under “Experimental Procedures” and illustrated in the figure with the vertical line. B, absorption spectra measured on salamander red cones in the native dark-adapted state (gray circles, n = 41), about 44 min after >90% bleach (black open circles, n = 23), and after treatment of bleached cones for 50–100 min with 11-cis-retinol (filled black circles, n = 44). Inset, normalized absorption spectra of salamander red cones before and after bleaching and regeneration with 11-cis-retinol (circles, n = 44) or 11-cis-retinal (triangles, n = 4).