The inositol 1,4,5-trisphosphate receptors

Abstract

The inositol (1,4,5)-trisphosphate receptors (InsP 3R) are the intracellular calcium (Ca 2+) release channels that play a key role in Ca 2+ signaling in cells. Three InsP 3R isoforms—InsP 3R type 1 (InsP 3R1), InsP 3R type 2 (InsP 3R2), and InsP 3R type 3 (InsP 3R3) are expressed in mammals. A single InsP 3R isoform is expressed in Drosophila melanogaster (DmInsP 3R) and Caenorhabditis elegans (CeInsP 3R). The progress made during last decade towards understanding the function and the properties of the InsP 3R is briefly reviewed in this chapter. The main emphasis is on studies that revealed structural determinants responsible for the ligand recognition by the InsP 3R, ion permeability of the InsP 3R, modulation of the InsP 3R by cytosolic Ca 2+, ATP and PKA phosphorylation and on the recently identified InsP 3R-binding partners. The main focus is on the InsP 3R1, but the recent information about properties of other InsP 3R isoforms is also discussed.