This gene encodes a member of the P2X purinergic receptor (purinoceptor) gene family which includes seven members (P2RX1 - P2RX7). P2X purinoceptors are a family of cation-permeable, ligand-gated ion channels that open in response to the binding of extracellular adenosine 5'-triphosphate (ATP). The encoded protein is a subunit of the trimeric P2X3 receptor ion channel which is expressed by sensory or autonomic neurons. A deficiency of the orthologous protein in mice is associated with reduced pain-related behavior and urinary bladder hyporeflexia.