Figure 8.

A: activity from single type-2 IPR recorded from the isolated nuclear envelope, showing modulation by Ca²⁺ and ATP at submaximal IP₃. Two modes of channel activity are evident; a long-lived Park mode that is mostly closed (blue bars), and a bursting mode refered to as Drive mode (red bars). The panel on the right shows the steady-state open probability as a function oc Ca²⁺ concentration, at a single fixed IP₃ concentration and two different ATP concentrations. B: schematic diagram of the IPR model [34]. C and O denote, respectively, closed and open states. The only transitions that are dependent on [Ca²⁺] and [IP₃] are q₄₂ and q₂₄, the transitions between the Park and Drive modes.