Klapperstück M, Büttner C, Böhm T, Schmalzing G, Markwardt F
Julius-Bernstein-Institut für Physiologie, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale, Germany.
Biochim Biophys Acta. 2000 Aug 25;1467(2):444-56. doi: 10.1016/s0005-2736(00)00245-5.
Human B lymphocytes express an ATP-gated ion channel (P2Z receptor), which shares similarities with the recently identified P2X7 receptor. Using gene specific primers, we have now isolated P2X7 cDNA from the total RNA of human B lymphocytes. This hP2X7 receptor subtype was expressed in Xenopus oocytes and electrophysiologically characterized. The hP2X7 receptor is similar to, but does not completely match, P2Z of human B cells. The hP2X7 receptors resemble the P2Z receptors with regard to the ATP concentration of half maximal activation, reproducibility, permeation characteristics and lack of desensitization of the ATP-evoked currents. However, in contrast to the native lymphocytic P2Z receptor, the time course of activation of hP2X7 displayed an additional linearly increasing current component. Furthermore, a second, small and slowly deactivating current component exists only in hP2X7 expressed in oocytes. The activation and deactivation kinetics as well as permeation characteristics of hP2X7 are different from rat P2X7 recently expressed in oocytes. Unlike in mammalian cells, hP2X7 expressed in Xenopus oocytes is not sufficient to induce large non-selective pores.
人B淋巴细胞表达一种ATP门控离子通道（P2Z受体），它与最近鉴定出的P2X7受体有相似之处。我们现在使用基因特异性引物从人B淋巴细胞的总RNA中分离出了P2X7 cDNA。这种hP2X7受体亚型在非洲爪蟾卵母细胞中表达并进行了电生理特性分析。hP2X7受体与人类B细胞的P2Z相似，但并不完全匹配。hP2X7受体在半最大激活的ATP浓度、重复性、通透特性以及ATP诱发电流不脱敏方面与P2Z受体相似。然而，与天然淋巴细胞P2Z受体不同，hP2X7激活的时间进程显示出一个额外的线性增加电流成分。此外，第二个小的且缓慢失活的电流成分仅存在于卵母细胞中表达的hP2X7中。hP2X7的激活和失活动力学以及通透特性与最近在卵母细胞中表达的大鼠P2X7不同。与在哺乳动物细胞中不同，在非洲爪蟾卵母细胞中表达的hP2X7不足以诱导形成大的非选择性孔道。
