TABLE I.

Commonly Used Abbreviations

O1	Open state O1
C1, C2	Closed states C1 and C2
tC1, tC2	Mean lifetimes of closed states C1 and C2
E1, E2	Exponential components E1 and E2
τE1, τE2	Time constants of exponential components E1 and E2
aE1,aE2	Areas of exponential components E1 and E2
{C1}	Distribution of all closed intervals arising from all sojourns to C1 in the gating sequence: O1-C1-O1 (see Table II, gating sequence 0). This distribution is a single exponential.
{C1C2}	Distribution of all closed intervals arising from all possible sojourns through both C1 and C2 in the gating sequences: O1-C1-(C2-C1-)n-O1, for n = 1 to infinity (see Table II and Eq. 6). This distribution is 0 at zero time, rises with an inflection to a peak, and then decays exponentially at longer times.
τ{C1}	Time constant of the {C1} distribution, which is given by tC1
τ{C1C2}	Time constant of the decaying phase of the {C1C2} distribution at long times
a{C1}	Area of {C1}
a{C1C2}	Area of {C1C2}