Abstract
Human B lymphocytes express an ATP-gated ion channel (P2Z receptor), which shares similarities with the recently identified P2X 7 receptor. Using gene specific primers, we have now isolated P2X 7 cDNA from the total RNA of human B lymphocytes. This hP2X 7 receptor subtype was expressed in Xenopus oocytes and electrophysiologically characterized. The hP2X 7 receptor is similar to, but does not completely match, P2Z of human B cells. The hP2X 7 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 hP2X 7 displayed an additional linearly increasing current component. Furthermore, a second, small and slowly deactivating current component exists only in hP2X 7 expressed in oocytes. The activation and deactivation kinetics as well as permeation characteristics of hP2X 7 are different from rat P2X 7 recently expressed in oocytes. Unlike in mammalian cells, hP2X 7 expressed in Xenopus oocytes is not sufficient to induce large non-selective pores.
Published Version
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