TABLE 5.

The effect of the αQ241W mutation on channel activation by P4S in the absence and presence of 3α5αP: open times

The open-time histograms were fitted to sums of two exponentials. The table gives the mean durations (OT1-2) and relative contributions (fraction OT1-2) for the open-time components. For data obtained in the absence of 3α5αP, the significance levels (ANOVA with Bonferroni correction) apply to comparison with the remaining three receptor types. For data obtained in the presence of P4S + 3α5αP, the significance levels apply to comparison with the same type of receptor activated by P4S in the absence of 3α5αP.

Receptor	P4S	3α5αP	OT1	Fraction OT1	OT2	Fraction OT2	n
			ms		ms
γβα-βα	1 mM		1.2 ± 0.2†,†,†	0.72 ± 0.16†,†,**	2.4 ± 0.6†,†,†	0.28 ± 0.16†,†,**	4
γβα-βα	1 mM	1 μM	0.6 ± 0.2**	0.48 ± 0.03*	12.5 ± 0.5***	0.52 ± 0.03*	4
γβαQ241W-βα	1 mM		1.0 ± 0.2†,†,†	0.58 ± 0.20†,†,*	3.2 ± 1.1†,†,†	0.42 ± 0.20†,†,*	8
γβαQ241W-βα	1 mM	1 μM	0.8 ± 0.4†	0.37 ± 0.06*	6.9 ± 1.9***	0.63 ± 0.06*	5
γβα-βαQ241W	1 mM		1.4 ± 0.7†,†,†	0.61 ± 0.28†,†,*	4.0 ± 1.2†,†,†	0.39 ± 0.28†,†,*	6
γβα-βαQ241W	1 mM	1 μM	1.1 ± 0.6†	0.33 ± 0.08*	11.8 ± 4.8**	0.67 ± 0.08*	7
γβαQ241W-βαQ241W	1 mM		0.8 ± 0.2†,†,†	0.27 ± 0.03**,*,*	3.4 ± 0.8†,†,†	0.73 ± 0.03**,*,*	6
γβαQ241W-βαQ241W	1 mM	1 μM	0.8 ± 0.4†	0.27 ± 0.13†	3.7 ± 1.4†	0.73 ± 0.13†	6

^*P < 0.05.

^**P < 0.01.

^***P < 0.001.

^†Not significant.