FIGURE 5.

Single channel trace recorded from an inside-out patch under basal conditions. (A, top) 200 s of history in the lifetime of a single GIRK1/GIRK4 channel excised into a bathing solution containing PKA-cs. No recombinant G_β1/γ2 was present. (A, lower traces) Single openings of the current trace shown on top, shown at expanded timescale. Single (1,2,3,4) as well as multiple openings (5,6) could be detected within a burst, resulting in at least two different kinetically distinguishable closed states. (B) Probability density functions of open (left) and closed (right) time distributions. +, experimental data; solid line, maximum likelihood fit. Both probability density functions (p.d.f.) were fit by the sum of two exponentials.