IP3R1: a multi-pass endoplasmic reticulum membrane receptor for inositol 1,4,5-trisphosphate, a second messenger that mediates the release of intracellular calcium. Plays a role in ER stress-induced apoptosis. Cytoplasmic calcium released from the ER triggers apoptosis by the activation of CaMKII, eventually leading to the activation of downstream apoptosis pathways. Part of a cGMP kinase signaling complex that includes alpha-actin, calponin H1, phospholamban, PKG1 and IP3R1. Widely expressed. The receptor contains a calcium channel in its C-terminal extremity. Its large N-terminal cytoplasmic region has the ligand-binding site in the N-terminus and modulatory sites in the middle portion immediately upstream of the channel region. Phosphorylation by PKA prevents the ligand-induced opening of the calcium channels. Belongs to the ryanodine-inositol 1,4,5-triphosphate receptor ca(2+) channel (rir-cac) family. Eight alternatively spliced isoforms have been described.
Protein type: Channel, ligand-gated; Membrane protein, integral; Channel, calcium; Membrane protein, multi-pass
Chromosomal Location of Human Ortholog: 3p26.1
Cellular Component: endoplasmic reticulum membrane; sarcoplasmic reticulum; membrane; endoplasmic reticulum; postsynaptic density; nucleolus; integral to membrane; nuclear inner membrane; platelet dense granule membrane; calcineurin complex
Molecular Function: protein binding; calcium ion transmembrane transporter activity; calcium channel inhibitor activity; intracellular ligand-gated calcium channel activity; phosphoinositide binding; inositol 1,4,5-triphosphate-sensitive calcium-release channel activity
Biological Process: epidermal growth factor receptor signaling pathway; negative regulation of calcium-mediated signaling; platelet activation; inositol phosphate-mediated signaling; voluntary musculoskeletal movement; fibroblast growth factor receptor signaling pathway; nerve growth factor receptor signaling pathway; signal transduction; post-embryonic development; endoplasmic reticulum calcium ion homeostasis; phospholipase C activation; calcium ion transport; release of sequestered calcium ion into cytosol; energy reserve metabolic process; response to hypoxia; innate immune response; vascular endothelial growth factor receptor signaling pathway; blood coagulation; regulation of insulin secretion
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