Figure 5.

Conditions that promote phosphorylation of native rod CNG channels prevent Ca²⁺/CaM inhibition. A, CNG currents from inside-out patches excised from ROS in response to 2 μm 8-Br-cGMP. In an ROS patch excised from a rod treated with control saline (top), Ca²⁺/CaM (50 μm Ca²⁺ plus 250 nm CaM) inhibits CNG current by ∼90% (top). In an ROS patch excised from a rod treated with 100 μm pervanadate for 1 hr, Ca²⁺/CaM had little effect (bottom). B, Population histograms of Ca²⁺/CaM inhibition of patches excised from ROS. Most patches from ROS exposed to control saline had CNG channels that were greatly inhibited by Ca²⁺/CaM (top), whereas the majority of patches from pervanadate-treated ROS had channels that were only slightly inhibited (bottom).