FIGURE 1.

Transient receptor potential canonical (TRPC) channels receptor-operated Ca²⁺ currents (ROCs). (A) Schematic representation of ROCs. Binding of an agonist to a G_q-protein-coupled receptor leads to phospholipase C (PLC) activation. The activated PLC hydrolyzes phosphatidylinositol 4,5-bisphosphate [PI(4,5)P₂] to produce of diacylglycerol (DAG) and IP₃. DAG and the reduction of PI(4,5)P₂ levels directly contribute to TRPC channels activation, while IP₃ triggers Ca²⁺ release from intracellular stores. (B) ROCs through TRPC7 channels. TRPC7 currents were induced using carbachol, a muscarinic receptor agonist (gray line, 100 μM). Left and right panels respectively display currents observed with low and high levels of muscarinic receptor expression (data from Itsuki et al., 2014). The vertical and horizontal gray scale bars indicate 200 pA and 15 s, respectively.