| Nomenclature | IP3R1 | IP3R2 | IP3R3 |
| HGNC, UniProt | ITPR1, Q14643 | ITPR2, Q14571 | ITPR3, Q14573 |
| Endogenous activators (EC50) | cytosolic ATP (< mM range), IP3 (endogenous; nM - μM range), cytosolic Ca2+ (Concentration range = < 7.5x10-4 M) | cytosolic Ca2+ (nM range), IP3 (endogenous; nM - μM range) | cytosolic Ca2+ (nM range), IP3 (endogenous; nM - μM range) |
| Activators (EC50) | adenophostin A (pharmacological; nM range), Ins(2,4,5)P3 (pharmacological; also activated by other InsP3 analogues) | adenophostin A (pharmacological; nM range), Ins(2,4,5)P3 (pharmacological; also activated by other InsP3 analogues) | – |
| Endogenous antagonists (IC50) | heparin (μg/ml) | heparin (μg/ml) | heparin (μg/ml) |
| Antagonists (IC50) | caffeine (mM range), decavanadate (μM range), PIP2 (μM range), xestospongin C (μM range) | decavanadate (μM range) | decavanadate (μM range) |
| Functional characteristics | Ca2+: (PBa/PK ∼6) single-channel conductance, ∼70 pS (50 mM Ca2+) | Ca2+: single-channel conductance, ∼70 pS (50 mM Ca2+), ∼390 pS (220 mM Cs+) | Ca2+: single-channel conductance, ∼88 pS (55 mM Ba2+) |
| Comment | IP3 R1 is also antagonised by calmodulin at high cytosolic Ca2+ concentrations | – | – |
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