Table 4.

Internalization of receptors.

Mutant	N	% Internalization		Mutant	N	% Internalization
		WT	Mutant			WT	Mutant
E23A	14	60.87 ± 5.94	61.15 ± 5.45	M42A	15	52.15 ± 6.68	60.32 ± 5.58
L24A	14	57.47 ± 6.38	63.81 ± 3.77	T43A	9	66.03 ± 5.30	69.75 ± 3.56**
E25A	12	57.65 ± 3.92	57.42 ± 4.45	A44L	12	71.16 ± 2.30	51.67 ± 3.59
E26A	12	71.10 ± 5.76	71.66 ± 3.79	Q45A	9	54.84 ± 2.69	27.45 ± 7.51**
S27A	12	58.40 ± 6.98	53.36 ± 7.22	Y46A	9	89.19 ± 2.05	56.83 ± 3.73***
P28A	14	62.65 ± 5.48	58.27 ± 2.85	E47A	9	68.72 ± 2.89	61.44 ± 2.85
E29A	21	63.40 ± 5.64	60.34 ± 2.86	C48A	15	57.04 ± 3.36	−14.65 ± 4.2***
D30A	9	65.40 ± 2.68	57.55 ± 5.80*	Y49A	18	49.80 ± 4.81	0.00 ± 9.34***
S31A	18	59.86 ± 5.98	64.01 ± 5.71	Q50A	15	68.58 ± 3.42	65.79 ± 3.06
I32A	15	64.96 ± 5.86	46.42 ± 4.43*	K51A	9	73.14 ± 2.87	76.48 ± 3.57
Q33A	15	63.92 ± 4.20	52.42 ± 4.14*	I52A	14	75.73 ± 4.89	51.41 ± 4.06***
L34A	11	54.84 ± 4.78	48.11 ± 4.84	M53A	9	68.28 ± 4.54	65.22 ± 3.41
G35A	20	62.51 ± 5.34	61.18 ± 3.24	Q54A	18	65.97 ± 6.18	63.03 ± 4.29
V36A	16	55.77 ± 6.11	44.86 ± 8.79	D55A	12	72.80 ± 1.96	65.32 ± 2.74
T37A	12	61.89 ± 5.12	54.01 ± 5.50	P56A	15	72.16 ± 2.78	56.22 ± 2.71***
R38A	15	54.54 ± 5.99	33.79 ± 5.02*	I57A	15	68.28 ± 6.03	59.61 ± 7.04
N39A	13	54.44 ± 3.13	62.20 ± 5.60	Q58A	9	69.32 ± 4.83	75.50 ± 3.29
K40A	9	67.16 ± 5.22	64.61 ± 4.02	Q59A	9	49.42 ± 3.45	59.90 ± 3.33
I41A	9	50.06 ± 6.03	16.92 ± 9.94***	A60L	9	55.80 ± 3.23	57.09 ± 4.14

The internalization of the WT receptor (as assessed by cell surface ELISA) was compared with that of each mutant in paired experiments. Values are % internalization, normalized against the cell surface expression prior to addition of CGRP and are means ± s.e.m, n = 9–18 derived from 3 to 6 independent experiments. *, **, ***, p > 0.05, 0.01 and 0.001, Mann–Whitney.