Pore-forming subunit of a voltage-gated ion channel required for sensory perception of sweet, bitter and umami tastes (By similarity). Specifically present in type II taste bud cells, where it plays a central role in sweet, bitter and umami taste perception by inducing ATP release from the cell, ATP acting as a neurotransmitter to activate afferent neural gustatory pathways (By similarity). Together with CALHM3, forms a fast-activating voltage-gated ATP-release channel in type II taste bud cells (TBCs) (By similarity). Acts both as a voltage-gated and calcium-activated ion channel: mediates neuronal excitability in response to changes in extracellular Ca(2+) concentration (, ). Has poor ion selectivity and forms a wide pore (around 14 Angstroms) that mediates permeation of Ca(2+), Na(+) and K(+), as well as permeation of monovalent anions . Acts as an activator of the ERK1 and ERK2 cascade . Triggers endoplasmic reticulum stress by reducing the calcium content of the endoplasmic reticulum . May indirectly control amyloid precursor protein (APP) proteolysis and aggregated amyloid-beta (Abeta) peptides levels in a Ca(2+) dependent manner .
Subcellular locations: Cell membrane, Endoplasmic reticulum membrane, Basolateral cell membrane
Colocalizes with HSPA5 at the endoplasmic reticulum . Localizes to the basolateral membrane of epithelial cells including taste cells (By similarity).
Predominantly expressed in adult brain. Detected also in retinoic acid-differentiated SH-SY5Y cells. Specifically expressed in circumvallate taste bud cells.