Figure 6. Kinetic model for the α1β3δ isoform.

A, a kinetic model for the α1β3δ isoform was derived from steady-state single-channel analysis and rapid kinetic analysis of currents from outside-out membrane patches. B, the rate constants in the model were optimized to best fit the time course of the α1β3δ macroscopic currents and the single-channel open, closed and burst properties (see Methods). O, open state; C, closed state; D, desensitized state. Units for all rate constants were s⁻¹ except for k_on (m⁻¹ s⁻¹). C, the optimized model currents were superimposed on averaged α1β3δ data traces for 2 ms (n= 4), 400 ms (n= 5) and 4000 ms (n= 4) applications of 1 mM GABA (application bars above traces). The same currents are depicted on an expanded time scale in the insets. Time calibrations for 2 and 400 ms applications and insets are 150 and 10 ms, respectively. Time calibrations for 4000 ms and inset are 1000 and 150 ms, respectively.