Intracellular calcium release channels.

Two classes of intracellular calcium release channels have been identified, the ryanodine receptor and the inositol 1,4,5-trisphosphate (InsP3) receptor. Characterizations of each receptor at the single channel level has shown that the channel types are functionally distinct. These two channels differ in the relative density and localization within the cell, in the mechanism of activation, in the regulation by Ca and ATP, and the sensitivity to pharmacological agents. The differences in the properties and regulation of the two types of intracellular calcium release channels are important for determining cell-specific responses to stimuli and allows the cell to adjust Ca signalling to the needs of the physiological state of the cell.