Table 1

Saturation binding of [³H](−)-EKC to κ mutants

Construct	K_D ± S.E.M.	B_max ± S.E.M.
Construct	K_D ± S.E.M.	Calcium Phosphate	FuGENE
	nM	fmol/mg protein
Wild type	0.49 ± 0.07	2136 ± 328	7935 ± 2293
K227A (TM 5)	0.26 ± 0.09	506 ± 147^1-160	694 ± 221^1-160
IHI290–292VQV (TM 6)	0.25 ± 0.04	692 ± 198^1-160	1056 ± 78^1-160
I316T (TM 7)	1.69 ± 0.01^1-160	2277 ± 328	7978 ± 2729

Receptors were labeled with concentrations of [³H](−)-EKC (18.1 Ci/mmol) ranging from 0.01 to 7.5 nM. Radioligand was incubated with membrane protein (50–200 μg) for 60 min at room temperature before harvesting by vacuum filtration. K_D andB_max values were determined from at least three independent experiments using membranes prepared from independent transfections. K_D was independent of transfection method. Mutants were compared to κ wild type using an unpaired Student's t test.

1-150 p < 0.05;
↵1-160 p < 0.01.