. Author manuscript; available in PMC: 2008 Nov 6.

Published in final edited form as: Biochemistry. 2007 Mar 24;46(15):4522–4531. doi: 10.1021/bi0622468

Table 1.

Characterization of CCK Receptor Binding and Activation^a

	Binding Characteristics								Intracellular Calcium Response
	Agonists				Antagonists				Agonists
Constructs	CCK		1,5-Benzodiazepine #1d		L-364,718		SR-27897		CCK		1,5-Benzodiazepine #1d
	K_i	B_max	K_i	B_max	K_i	B_max	K_i	B_max	EC₅₀	E_max	EC₅₀	E_max

	nM	pmol/mg protein	nM	pmol/mg protein	nM	pmol/mg protein	nM	pmol/mg protein	nM	nM	nM	nM
WT	0.5 ± 0.1	0.7 ± 0.1	4.6 ± 0.3	10.3 ± 0.2	4.7 ± 1.2	14.1 ± 1.4	5.3 ± 1.0	22.9 ± 3.9	0.03 ± 0.01	236 ± 30	6.1 ± 0.4	213 ± 26
K187A	0.4 ± 0.1	0.6 ± 0.2	4.7 ± 0.3	9.0 ± 1.1	1.1 ± 0.1	12.0 ± 2.5	3.1 ± 0.6	20.4 ± 3.0	0.1 ± 0.1	232 ± 39	122 ± 30	198 ± 37
K187D	0.4 ± 0.1	0.5 ± 0.1	4.7 ± 0.7	9.9 ± 1.1	3.2 ± 0.5	12.5 ± 1.7	2.7 ± 0.4	18.8 ± 0.7	7.0 ± 1.0	120 ± 29	N.D.	N.D.
WT)31–429	0.7 ± 0.1	5.7 ± 1.5	4.3 ± 0.5	4.7 ± 1.3					0.13 ± 0.03	228 ± 32	7.6 ± 1.8	191 ± 39
K187D)31–429	0.9 ± 0.1	1.4 ± 0.4	7.7 ± 2.2	1.4 ± 0.4					0.16 ± 0.04	240 ± 46	25.4 ± 4.0	175 ± 40
D5K	1.3 ± 0.2	10.0 ± 1.9	4.3 ± 0.9	4.6 ± 1.5					0.29 ± 0.06	100 ± 24	9.0 ± 2.0	105 ± 27
D5K(K187D)	1.6 ± 0.2	7.9 ± 2.0	4.5 ± 0.9	1.4 ± 0.2					0.03 ± 0.01	102 ± 28	28.8 ± 5.6	96 ± 19

Shown are K_i and B_max values for ligand binding to membranes prepared from cells expressing each of the noted CCK receptor constructs. Shown also are EC₅₀ and E_max values (delta changes from basal values, nM) for ligand-stimulated intracellular calcium responses in these cells. All values represent the means ± S.E.M. of data from at least three independent experiments. N.D., not detected.