Estimation of ion Channel Kinetics from Macroscopic Recordings

Luciano Moffatt
2011 Biophysical Journal  
contributes to GABAR subunit-subunit interfaces. We studied gating properties and surface expression of wild type (wt) a6b2g2 and mutant a6(Q237R) b2g2 receptors expressed in HEK293T cells. Transient currents were evoked using ultrafast application of 400-msec pulses of saturating GABA (1 mM) applied to excised outside-out macropatches. Peak amplitudes of a6 (Q237R)b2g2 currents were not reduced but a6(Q237R)b2g2 currents had slower activation (~1.9 msec), slower and more desensitization (~60
more » ... , and faster deactivation (~2-fold) than wt currents. On-cell a6(Q237R)b2g2 and a6b2g2 single channel currents had similar mean open durations, but opening and burst frequencies were significantly higher for mutant than for wt currents. We assessed surface and total cellular expression of wt and mutant receptors using flow cytometry. Co-expression of a6(Q237R) with b2 and g2L subunits resulted in no significant reduction in total or surface expression of any subunit. We concluded that this mutation alters gating, but not trafficking, of a6b2g2 GABARs.
doi:10.1016/j.bpj.2010.12.1697 fatcat:a45mhhfyvvbqpehxhp2zhq6w2a