Collo G, North R A, Kawashima E, Merlo-Pich E, Neidhart S, Surprenant A, Buell G
Glaxo Institute for Molecular Biology, Geneva, Switzerland.
J Neurosci. 1996 Apr 15;16(8):2495-507. doi: 10.1523/JNEUROSCI.16-08-02495.1996.
Two new P2X receptor cDNAs (P2X5 and P2X6) were isolated and expressed. All six proteins are 36-48 percent identical and seem to have two transmembrane segments with a large extracellular loop. Functionally, P2X5 and P2X6 receptors most resemble P2X2 and P2X4; they desensitize only slowly and do not respond to alpha beta methylene-ATP. P2X6 receptors, like P2X4, receptors, are not blocked by the antagonists suramin and pyridoxal-5-phosphate-6-azophenyl-2',4'-disulfonic acid. P2X6 and P2X5 receptors express at lower levels than P2X1-P2X4 receptors do, perhaps indicating that they do not normally form homomultimeric channels. P2X6 and P2X4 are the receptors expressed most heavily in brain, where their RNAs have a widespread and extensively overlapping distribution. The spinal cord expresses all receptors except P2X3. P2X2, P2X4, and P2X6, are the most abundant in the dorsal horn. Sensory neurons of the trigeminal, dorsal root, and nodose ganglia express all six RNAs; P2X3 is found only there. The functional properties and tissue distribution of these six P2X receptors indicate new roles for ATP-gated ion channels.
分离并表达了两种新的P2X受体cDNA（P2X5和P2X6）。所有六种蛋白质的同源性为36%至48%，似乎有两个跨膜区段和一个大的细胞外环。在功能上，P2X5和P2X6受体与P2X2和P2X4最为相似；它们脱敏缓慢，对αβ亚甲基ATP无反应。与P2X4受体一样，P2X6受体不受拮抗剂苏拉明和磷酸吡哆醛-5-磷酸-6-偶氮苯-2',4'-二磺酸的阻断。P2X6和P2X5受体的表达水平低于P2X1 - P2X4受体，这可能表明它们通常不形成同型多聚体通道。P2X6和P2X4是在脑中表达最丰富的受体，它们的RNA分布广泛且有大量重叠。脊髓表达除P2X3外的所有受体。P2X2、P2X4和P2X6在背角中最为丰富。三叉神经节、背根神经节和结状神经节的感觉神经元表达所有六种RNA；仅在这些部位发现P2X3。这六种P2X受体的功能特性和组织分布表明ATP门控离子通道有新的作用。
