Module 3: Figure conformational coupling hypothesis
A conformational coupling hypothesis of capacitative Ca2+ entry.
The conformational coupling hypothesis proposes that there is an interaction between the store-operated channel (SOC) in the plasma membrane and some coupling protein that detects Ca2+ depletion of the endoplasmic reticulum (ER). A. In the resting state when the ER is full, there is no entry. B. When receptors are activated to produce InsP3, this activates InsP3Rs to induce a local depletion of ER, which then activates the coupling protein to induce a conformational change that is responsible for switching on entry through the SOC channels. For further details of some of the proposed coupling mechanisms, see Module 3: Figure STIM-induced Ca2+ entry.