Characterization of N-terminal P2X7R mutants. (Left) Representative traces of currents generated by a 40-s application of 100 μM BzATP by WT and mutant receptors expressed in HEK293 cells. Notice that BzATP induced monophasic currents in cells expressing T15E, T15K, and T15W mutants and biphasic current in all other mutants. Receptor deactivation was delayed in cells expressing T15E, T15K, T15W, and K17A mutants. Cells were bathed in KR buffer. (Middle and right) Comparison of the permeability of channels to NMDG+ (middle) and NMEA+ (right). Change in time courses are shown from left to right, and vertical dotted lines indicate the reversal potential for WT receptors at the beginning and at the end of a 40-s application of 100 μM BzATP. Cells were bathed in NMDG+- or NMEA+-containing KR buffer. Mean ± SEM values are shown in Table I.
