Inositol 1,4,5-trisphosphate receptor (IP3R)

Intracellular calcium release in hepatocytes is primarily mediated by the inositol 1,4,5-trisphosphate receptor (IP3R), a ligand-gated ion channel located on the endoplasmic reticulum membrane. Upon activation by second messenger IP3 (generated via PLC activation after stimulation by extracellular ligands like ATP, vasopressin, glucagon, and epinephrine), IP3R releases Ca^2+ from the ER into the cytosol. This rise in cytoplasmic calcium regulates diverse functions in the liver, such as cellular metabolism, secretion, proliferation, and the response to injury. Increases in intracellular calcium can also be mediated by ryanodine receptors, but in hepatocytes, IP3Rs are dominant. Pharmacological and pathological modulation of this pathway is implicated in liver regeneration, carcinogenesis, and liver injury responses.

Other names

IP3 receptorInsP3 receptorITPRITPR1/2/3calcium release channel

Ligand (IP3)-gated channel opening to release calcium from the endoplasmic reticulum (ER); Modulation by signaling pathways (PLC, G-protein coupled receptors/agonists such as ATP, vasopressin, glucagon, epinephrine)