Table 1. The effect of patch excision on the activation by ACh of receptors containing the αY93F subunit.

	αY93Fβγδ		αY93Fβδε
	c/a	i/o	c/a	i/o
A. Kinetic analysis
k+ (μm−1 s−1)	14.1 ± 4.4	19.5 ± 11.6	8.2 ± 1.2	7.6 ± 1.5
k− (s−1)	7061 ± 2260	12 184 ± 7413	5153 ± 763	6560 ± 1357
Kd (μm)	501 ± 223	625 ± 532	628 ± 93	863 ± 247
β (s−1)	(1016 ± 99)	(1078 ± 144)	(1220 ± 269)	(1097 ± 258)
α (s−1)	436 ± 11	777 ± 23	2919 ± 65	2434 ± 49
β/α	2.3 ± 0.2	1.4 ± 0.2	0.42 ± 0.09	0.45 ± 0.11
B. Concentration response
Po,max	0.76 ± 0.12	0.55 ± 0.02	0.38 ± 0.03	0.35 ± 0.01
Po EC50 (μm)	631 ± 182	701 ± 49	1145 ± 170	1424 ± 66
β (s−1)	1016 ± 99	1078 ± 129	1220 ± 269	1097 ± 258
α (s−1)	401 ± 54	822 ± 84	1708 ± 353	1866 ± 252

A. Parameter estimates from the analysis of singlechannel activity within clusters. Rate constants were calculated using the programs SKM and MIL as described in Methods. Data were filtered at 4 kHz; dead time was set at 45 μs. For αY93βγδ receptors the data for cellattached patches consisted of results from 2 patches (1 with 0.5 mm ACh, 1 with 1 mm ACh, 3212 events total) while the data for insideout patches were obtained from two different patches (1 with 0.5 mm ACh, 1 with 1 mm ACh, 2382 events total). For αY93βδε receptors the data for cellattached patches consisted of results from 1 patch (0.5 mm ACh, 3924 events) while the data for insideout patches were obtained from two different patches (1 with 0.5 mm ACh, 1 with 1 mm ACh, 5288 events total). Both data sets were analysed assuming identical agonist binding sites. The channel opening rate constant (β) was constrained to the value obtained from the saturation of the effective opening rate curve (Fig. 4). Values are given as best fit ±s.d. B. Parameter estimates from the concentration–response curves (see Fig. 4). Values are given as best fit ±s.d. Abbreviations: c/a, cellattached; i/o, insideout.