Characteristics of P2X7 receptors from human B lymphocytes expressed in Xenopus oocytes

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 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 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 calls, hP2X(7) expressed in Xenopus oocytes is nor sufficient to induce large non-selective pores. (C) 2000 Elsevier Science B.V. All rights reserved.