COEXPRESSION OF P2X(2) AND P2X(3) RECEPTOR SUBUNITS CAN ACCOUNT FOR ATP-GATED CURRENTS IN SENSORY NEURONS

Cation-selective P2X receptor channels were first described in sensory neurons(1-4) where they are important for primary afferent neurotrans mission and nociception(5,6). Here we report the cloning of a compleme ntary DNA (P2X(3)) from rat dorsal root ganglia that had properties di ssimilar to those of sensory neurons. We also found RNA for (P2X(1)) ( ref. 7), (P2X(2)) (ref. 8) and P2X(4) (ref. 9) in sensory neurons; cha nnels expressed from individual cDNAs did not reproduce those of senso ry ganglia. Coexpression of P2X(3) with P2X(2), but not other combinat ions, yielded ATP-activated currents that closely resembled those in s ensory neurons. These properties could not be accounted for by additio n of the two sets of channels, indicating that a new channel had forme d by subunit heteropolymerization. Although in some tissues responses to ATP can be accounted for by homomeric channels(1,7-10), our results indicate that ATP-gated channels of sensory neurons may form by a spe cific heteropolymerization of P2X receptor subunits.