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IP3 receptors C

Unless otherwise stated all data on this page refer to the human proteins. Gene information is provided for human (Hs), mouse (Mm) and rat (Rn).


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The inositol 1,4,5-trisphosphate receptors (IP3R) are ligand-gated Ca2+-release channels on intracellular Ca2+ store sites (such as the endoplasmic reticulum). They are responsible for the mobilization of intracellular Ca2+ stores and play an important role in intracellular Ca2+ signalling in a wide variety of cell types. Three different gene products (types I-III) have been isolated, which assemble as large tetrameric structures. IP3Rs are closely associated with certain proteins: calmodulin (CALM2, CALM3, CALM1, P62158) and FKBP (and calcineurin via FKBP). They are phosphorylated by PKA, PKC, PKG and CaMKII.

Channels and Subunits

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Targets of relevance to immunopharmacology are highlighted in blue

IP3R1 C Show summary »

Target Id 743
Nomenclature IP3R1
Previous and unofficial names INSP3R1 | IP3R1 | SCA15 | SCA16 | spinocerebellar ataxia 15 | spinocerebellar ataxia 16 | I145TR | inositol 1,4,5-triphosphate receptor 1 | InsP3R | IP3 receptor | InsP3R type I | Ip3r | Itpr-1 | opt | Pcp1 | inositol 1 | inositol 1,4,5-trisphosphate receptor 1
Genes ITPR1 (Hs), Itpr1 (Mm), Itpr1 (Rn)
Ensembl ID ENSG00000150995 (Hs), ENSMUSG00000030102 (Mm), ENSRNOG00000007104 (Rn)
UniProtKB AC Q14643 (Hs), P11881 (Mm), P29994 (Rn)
Endogenous activators
cytosolic Ca2+ Concentration range: < 7.5x10-4 M
cytosolic ATP (< mM range)
IP3 (endogenous; nM - μM range)
adenophostin A (pharmacological; nM range)
inositol 2,4,5-trisphosphate (pharmacological; also activated by other InsP3 analogues)
caffeine (mM range)
PIP2 (μM range)
decavanadate (μM range)
xestospongin C (μM range)
Functional characteristics Ca2+: (PBa/PK ~6) single-channel conductance
~70 pS (50 mM Ca2+)
Comment IP3 R1 is also antagonised by calmodulin at high cytosolic Ca2+ concentrations

IP3R2 C Show summary »

IP3R3 C Show summary »


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Further reading

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How to cite this family page

Database page citation:

IP3 receptors. Accessed on 20/02/2024. IUPHAR/BPS Guide to PHARMACOLOGY,

Concise Guide to PHARMACOLOGY citation:

Alexander SPH, Mathie AA, Peters JA, Veale EL, Striessnig J, Kelly E, Armstrong JF, Faccenda E, Harding SD, Davies JA et al. (2023) The Concise Guide to PHARMACOLOGY 2023/24: Ion channels. Br J Pharmacol. 180 Suppl 2:S145-S222.