P2X23

P2X23 is not a widely recognized receptor subtype in the P2X purinergic receptor family. In standard nomenclature, the P2X family comprises subtypes P2X1 through P2X7, encoded by the P2RX1–P2RX7 genes. Occasional references to P2X23 are thought to reflect either a typographical error or a shorthand for the P2X2/3 heteromer, a functional channel formed by the coassembly of P2X2 and P2X3 subunits. There is no consensus on a separate P2X23 homomeric receptor in humans or most other species.

Biophysical and structural features: P2X receptors are trimeric ATP-gated ion channels with two transmembrane domains per subunit. The P2X3 and P2X2 subunits can form homomeric channels as well as the P2X2/3 heteromer. The P2X2/3 channel exhibits biophysical properties distinct from the homomeric receptors, including differences in ATP sensitivity and desensitization kinetics.

Distribution and function: P2X receptors are widely expressed in the nervous system; P2X3 and the P2X2/3 heteromer are prominently present in sensory neurons of dorsal root and trigeminal ganglia, where they contribute to synaptic transmission and nociceptive signaling. The heteromer has been implicated in visceral sensation and inflammatory pain, and is considered a potential target for analgesic therapy.

Pharmacology and research relevance: ATP is the natural agonist; selective antagonists for P2X3 and P2X2/3 have been developed, enabling functional studies and therapeutic exploration. Because of their role in pain signaling, P2X2/3-containing receptors are investigated as targets for chronic pain, cough, and other sensory disorders.