Table 2.

Charge distribution and measured Pf-values of the indicated 16 nAChRs.

sp.	Type	Ext. domain			TM2				Int.	Pf (%)	References
			{−5′−4′} cytopl. ring	{−1′} inter. ring	{19′}	{20′} extrac. ring	{21′ 24′}	{25′ 29′}	TM3 TM4
H	α4β4	−12.75	−5	−5	0	0	0	−2.5	36.5	1.5 ± 0.2	Lax et al., 2002
M	αβγδ	−63	−3	−4	0	−1	1	0	22.6	2.1 ± 0.3	Ragozzino et al., 1998
C	α4β4	−17.25	−5	−5	0	0	0	−2.5	35	2.1 ± 0.2	Lax et al., 2002
H	α4β2	−34.25	−5	−5	0	0	0	−2.5	37	2.6 ± 0.3	Lax et al., 2002
H	α3β4	−18.75	−5	−5	0	0	0	−2.5	26.5	2.7 ± 0.2	Lax et al., 2002
H	αβγδ	−53	−3	−4	0	−1	1	0	23.4	2.9 ± 0.2	Fucile et al., 2006a
C	α4β2	−25	−5	−5	0	0	0	−2.5	46.5	2.9 ± 0.5	Ragozzino et al., 1998
H	(β2α4)2α4	−31.7	−5	−5	0	−1	0	−2	39	4.0 ± 0.4	Sciaccaluga et al., 2015
M	αβεδ	−69	−4	−4	0	−2	1	0	15.2	4.2 ± 1.0	Ragozzino et al., 1998
C	α3β4	−23	−5	−5	0	0	0	−2.5	4.5	4.4 ± 0.5	Lax et al., 2002
H	αβεδ	−55.9	−4	−4	0	−2	1	0	17.8	7.2 ± 1.1	Fucile et al., 2006a
H	(β2α4)2α5	−32.1	−5	−5	−1	−1	0	−1	35	8.2 ± 0.7	Sciaccaluga et al., 2015
M	(β2α4)2α5	−32	−5	−5	−1	−1	0	−1	43.6	8.8 ± 1.1	Sciaccaluga et al., 2015
R	α7	−23.5	−5	−5	0	−5	0	−5	18	8.8 ± 1.5	Fucile et al., 2003
H	α7	−23	−5	−5	0	−5	0	−5	16	11.4 ± 1.3	Fucile et al., 2003
R	α9α10	−40.75	−2.5	−5	0	−5	0	−5	55.5	22 ± 4	Fucile et al., 2006b

H, human; M, mouse; R, rat; C, chicken. In brackets the positions of amino acid residues according to Miller (1989). Pf, fractional Ca²⁺ current. Charge values are expressed in natural unit of electric charge (nuec).