It has been demonstrated that TrpC1 and TrpC5 are subunits of a heteromeric neuronal channel in mammalian brain. TrpC5 is thought to form a receptor-activatd non-selective permeant cation channel. It is probably operated by a phosphatidylinositol second messenger system activated by receptor kinases or G-protein coupled receptors. It has also been shown to be calcium-selective and it may be also activated by intracellular calcium store depletion. TrpC5 protein was shown to be present in hippocampal neuronal growth cones, neuronal cell bodies, areas consistent with new synapse formation, and cytoplasmic transport vesicles along neuronal processes. TrpC5 is expressed in brain with higher levels in fetal brain. Influxes of calcium via voltage-gated channels play a role in neuronal outgrowth and it was suggested that TrpC5 is a candidate for the regulation of calcium waves.