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InsP3 hosts a receptor get-together
Intracellular Ca2+ concentration is regulated in part by the activity of inositol-1,4,5-trisphosphate (InsP3)
receptors (InsP3Rs). InsP3R tetramers function as Ca2+ channels that release Ca2+ from the endoplasmic reticulum in response to InsP3 and Ca2+. Low concentrations of InsP3 can stimulate a blip of Ca2+ release from a single InsP3R channel; the Ca2+ released then stimulates additional InsP3Rs, generating a puff of Ca2+. This puff of Ca2+ feeds forward to stimulate subsequent wavesof Ca2+ release as InsP3 and Ca2+ concentrations increase. However, the biochemical mechanism that underlies receptor clustering...