TABLE 3.

Potency (pEC₅₀), affinity (pK_a) and coupling efficacy (log τ) values for cAMP production at the CLR co-expressed with each RAMP, stimulated with various agonists measured in HEK-293 cells in the presence and absence of pertussis toxin

Data are the mean ± S.E. of n individual data sets. Statistically different between PTX-treated and untreated was determined using Student's t test (*, p < 0.05; **, p < 0.01; ***, p < 0.001; and ****, p < 0.0001).

	Untreated					Treated
	pEC50a	Emaxb	pKac	log τd	n	pEC50a	Emaxb	pKac	log τd	n
RAMP1
CGRP	9.66 ± 0.2	47.07 ± 2.2	9.43 ± 0.2	−0.11 ± 0.04	9	9.65 ± 0.2	44.95 ± 2.2	9.33 ± 0.3	−0.11 ± 0.07	6
AM	7.93 ± 0.2	48.06 ± 2.5	7.67 ± 0.2	−0.09 ± 0.05	9	8.14 ± 0.07	72.17 ± 1.7***	7.66 ± 0.2	0.36 ± 0.1**	6
AM2	7.93 ± 0.2	46.10 ± 4.1	7.70 ± 0.2	−0.11 ± 0.07	9	9.15 ± 0.1*	72.15 ± 2.4***	8.56 ± 0.3	0.4 ± 0.1**	6
RAMP2
CGRP	9.00 ± 0.2	36.97 ± 2.4	8.82 ± 0.2	−0.27 ± 0.05	9	8.25 ± 0.4	56.27 ± 1.4***	7.92 ± 0.2*	0 0.1 ± 0.06**	6
AM	10.35 ± 0.1	56.33 ± 1.6	10.00 ± 0.1	0.07 ± 0.02	9	10.16 ± 0.07	56.07 ± 1.1	9.83 ± 0.2	0.07 ± 0.02	6
AM2	7.46 ± 0.2	36.61 ± 3.5	7.24 ± 0.2	−0.29 ± 0.07	9	9.13 ± 0.1**	56.05 ± 2.2***	8.84 ± 0.2**	0.1 ± 0.06*	6
RAMP3
CGRP	7.75 ± 0.3	22.38 ± 2.6	7.64 ± 0.3	−0.54 ± 0.07	8	8.90 ± 0.1*	32.61 ± 1.5*	8.74 ± 0.2*	−0.29 ± 0.06	7
AM	8.98 ± 0.2	32.00 ± 1.5	8.83 ± 0.1	−0.33 ± 0.03	8	9.10 ± 0.2	35.95 ± 2.2	8.94 ± 0.2	−0.34 ± 0.05	7
AM2	9.10 ± 0.2	21.92 ± 1.7	9.08 ± 0.2	−0.51 ± 0.06	8	8.74 ± 0.2	44.35 ± 2.7****	8.43 ± 0.1*	−0.07 ± 0.07***	7

^a The negative logarithm of the agonist concentration required to produce a half-maximal response.

^b The maximal response to the ligand expressed as a percentage of the maximal cAMP production as determined using 100 μm forskolin stimulation in the presence of pertussis toxin treatment.

^c The negative logarithm of the equilibrium disassociation constant for each ligand generated through use of the operational model of agonism (34).

^d Log τ is the coupling efficiency parameter of each ligand.