Fig. 4.

The R214C mutation resulted in reduced surface and total expression levels of the α1 subunit, and altered the kinetic and single channel properties of GABA_ARs. a Representative blots of biotinylation samples for surface receptor expression and cell lysates for total receptor expression from HEK293 cells expressing either WT or R214C GABA_ARs. b Quantification of surface α1 subunits normalized to Na⁺/K⁺ ATPase (n = 6), and total α1 subunits normalized to β-actin (n = 10). Statistical differences were determined using student’s t-test by comparing to expression levels of WT GABA_AR expressing cells (***p < 0.001). c Representative traces of GABA currents recorded in excised macro-patch membrane under outside-out configuration from WT or R214C GABA_AR expressing cells. Currents were evoked by rapidly perfusion of 10 mM GABA to the membrane patch for 400 ms. Quantification of averaged peak current amplitudes (d), 10–90% rise time (e), deactivation rate (f) and desensitization (g) in WT (n = 8) or R214C (n = 8) GABA_AR expressing cells. h Representative single channel current traces recorded under cell-attached configuration with a pipette containing GABA (1 mM) at a holding potential of + 100 mV from cells expressing WT or R214C GABA_ARs. Quantified average of conductance (i), opening frequency (j), mean open time (k), total open time (l), total closed time (m), and open channel probability (n) of WT (n = 10) or R214C (n = 13) GABA_ARs. Statistical differences were determined using student’s t-test by comparing to WT GABA_AR cells (*p < 0.05, **p < 0.01, ***p < 0.001)