Structure and function of IP3 receptors.

The molecular, structural and functional characteristics of the intracellular Ca2+ release channel activated by inositol 1,4,5-trisphosphate (IP3), also named IP3 receptor (IP3R), are described here. We also discuss the differences in primary structure, expression and modulation of the receptor subtypes and their physiological roles. The similarity and differences between the IP3R and the other intracellular Ca2+ channel, the ryanodine receptor, are briefly presented.