Figure 4.

GCAP1 and GCAP2 contribute to the light adaptation capacity of cones. a–c, responses of cones to 7-s steps of light with a 1-ms flash delivered 4.5 s after the step onset from isolated retinas of control Gnat1^−/− (a), Gcaps^−/− Gnat1^−/− (b), and Gcap1^−/− Gnat1^−/− (c) mice obtained using ex vivo ERG recordings. Smooth gray traces plot Equation 3 with best fitting parameters A₁, τ₁, and τ₂. See “Results” for numerical values and statistical analysis. d, sensitivity (S_F) normalized (Norm.) with the dark-adapted sensitivity (S_F,D) of cones as a function of background light intensity (I) in control Gnat1^−/− (black), Gcaps^−/− Gnat1^−/− (green), and Gcap1^−/− Gnat1^−/− (red). Smooth lines plot Equation 2 with I₀ of 13,500 photons μm⁻² s⁻¹ (n = 1), 6,700 photons μm⁻² s⁻¹ (n = 1.4), and 4,100 photons μm⁻² s⁻¹ (n = 1) for control Gnat1^−/− (black), Gcaps^−/− Gnat1^−/− (green), and Gcap1^−/− Gnat1^−/− (red). n = 3 mice (four retinas) for each genotype. Error bars give S.E.