Salih S G, Housley G D, Burton L D, Greenwood D
Department of Physiology, Faculty of Medicine and Health Science, University of Auckland, New Zealand.
Neuroreport. 1998 Jan 26;9(2):279-82. doi: 10.1097/00001756-199801260-00019.
Spiral ganglion neurones in rat cochlea express three different isoforms of the P2X2 receptor subunit which assemble into ATP-gated ion channels. Two of these P2X2R subunit isoforms have previously been detected in other auditory tissues. The third isoform (designated P2X2-3R) has not been described. This isoform lacks 39 bp immediately prior to the stop codon, corresponding to a 13 amino acid deletion of the extreme C-terminus domain. Using direct in situ RT-PCR, expression of P2X2R mRNA was confined to a subpopulation of type I spiral ganglion neurones. This study supports a role for extracellular ATP as a neurotransmitter for a discrete population of auditory neurones where variation in P2X2R isoform assembly may confer functional heterogeneity, including enhanced desensitization.
大鼠耳蜗的螺旋神经节神经元表达P2X2受体亚基的三种不同同工型，它们组装成ATP门控离子通道。此前已在其他听觉组织中检测到其中两种P2X2R亚基同工型。第三种同工型（命名为P2X2-3R）尚未见报道。该同工型在终止密码子之前紧邻处缺少39个碱基对，相当于极端C末端结构域缺失13个氨基酸。采用直接原位逆转录聚合酶链反应，P2X2R mRNA的表达局限于I型螺旋神经节神经元的一个亚群。本研究支持细胞外ATP作为离散听觉神经元群体的神经递质发挥作用，其中P2X2R同工型组装的差异可能导致功能异质性，包括脱敏增强。
