P2X2

P2X2 is a subunit of the P2X receptor family, ATP-gated ion channels. It is encoded by the P2RX2 gene in humans. P2X receptors form trimeric channels; P2X2 can assemble as homomeric P2X2 receptors or as part of heteromeric complexes with other subunits, most notably P2X3 to form P2X2/3 receptors found in sensory neurons.

Activation: Extracellular ATP binds to the receptor, opening a cation-selective pore. The channel passes Na+, K+, and Ca2+, with Ca2+ influx contributing to signaling cascades. The kinetics vary with subunit composition; P2X2 homomers desensitize slowly, whereas P2X2/3 receptors show more rapid desensitization.

Distribution: P2X2 transcripts are found in parts of the peripheral nervous system, including dorsal root ganglia and nodose (vagal) ganglia, as well as in other tissues. Functions include modulation of neurotransmission, nociceptive signaling, and taste perception, among others.

Pharmacology: Receptors containing P2X2 are blocked by broad-spectrum P2X antagonists such as suramin and PPADS; selective pharmacology is limited, but research distinguishes P2X2-containing channels from homomeric P2X3 or P2X1/5 families.

Genetics and research: The P2RX2 gene encodes the P2X2 subunit. Studies in animals and humans investigate roles in pain, vestibular function, and hearing; mutations can affect purinergic signaling and sensory processing in certain contexts.