. 1997 May 13;94(10):5000–5005. doi: 10.1073/pnas.94.10.5000

Table 1.

Prediction of the subunit stoichiometry of the active form of the M₂ ion channel protein

f_M2tag (f_wt)	Inh_mix	In (Inh_mix)
f_M2tag (f_wt)	Inh_mix	In (f_wt)
0.84	0.50	3.98
0.91	0.69	3.93
0.85	0.51	4.14
0.79	0.38	4.10
0.77	0.34^*	4.12
0.80	0.38^*	4.34
0.85	0.50^*	4.27
0.71	0.24^*	4.17
0.85	0.49^*	4.38
	mean n = 4.16 ± 0.17

The fraction of blocked currents at equilibrium, Inh_mix, was determined using 100 μM of amantadine and 20 μM of amantadine (∗). Equilibrium inhibition is shown (2 min for 100 μM of amantadine and 6 min for 20 μM of amantadine). The inhibited fraction for the M₂tag protein, Inh_wt, at both 100 μM and 20 μM of amantadine was 100% at equilibrium (10 determinations). When these values for fraction-blocked current were substituted into Eq. 7, a value of n close to four was obtained. In this experiment, a high ratio of f_wt (70–90%) was used. This condition favors a small R term (Eq. 6) by shifting the channel population towards the fully amantadine-sensitive form, allowing an accurate estimate of n to be made.