Binding of IP3 to IP3 receptor

Stable Identifier
R-HSA-139941
Type
Reaction
Species
Homo sapiens
Compartment
Locations in the PathwayBrowser
Summation

The IP3 receptor (IP3R) is an intracellular calcium release channel that mobilizes Ca2+ from internal stores in the ER to the cytoplasm. Though its activity is stimulated by IP3, the principal activator of the IP3R is Ca2+. This process of calcium-induced calcium release is central to the mechanism of Ca2+ signalling. The effect of cytosolic Ca2+ on IP3R is complex: it can be both stimulatory and inhibitory and can the effect varies between IP3R isoforms. In general, the IP3Rs have a bell-shaped Ca2+ dependence when treated with low concentrations of IP3; low concentrations of Ca2+ (100?300 nM) are stimulatory but above 300 nM, Ca2+ becomes inhibitory and switches the channel off. The stimulatory effect of IP3 is to relieve Ca2+ inhibition of the channel, enabling Ca2+ activation sites to gate it.
Functionally the IP3 receptor is believed to be tetrameric, with results indicating that the tetramer is composed of 2 pairs of protein isoforms.

Literature References
PubMed ID Title Journal Year
11413485 The versatility and universality of calcium signalling

Berridge, MJ, Lipp, P, Bootman, MD

Nat Rev Mol Cell Biol 2000
Participants
Participant Of
Orthologous Events