Figure 6.

Conductance substates of the InsP₃R channels observed in nuclear patches obtained from r-InsP₃R-3 cRNA-injected oocytes. (A) Current trace showing a transition of an InsP₃R channel from the small (S) conductance state to the main (M) conductance state in symmetric solutions containing 0 mM Mg²⁺; [Ca²⁺]_i = 1,150 nM. (B) Current trace showing an InsP₃R channel in the rare half (H) conductance state in symmetric solutions containing 0 mM Mg²⁺; [Ca²⁺]_i = 255 nM. (C) Current trace showing an InsP₃R channel in the normal and flicker kinetic modes in symmetric 2.5 mM Mg²⁺; [Ca²⁺]_i = 940 nM. F₁ and F₂ denote the conductance states in the flicker kinetic mode.