TABLE 1.

Binding and transactivation characteristics of ER-β ligands, β-LGND1, and β-LGND2

Ligand binding assays are shown in the 2nd to 6th columns. Binding affinity was determined using purified rat ER-α and ER-β LBD and [³H]estradiol as described under “Materials and Methods.” Transactivation assays are shown in the 7th and 8th columns. HEK293 cells were transfected with 0.25 μg of ERE-LUC, 0.5 ng of CMV-Renilla-LUC, and 25 ng of pCR3.1 ER-α or 50 ng pCR3.1 ER-β and treated with the ligands for 24 h. The cells were lysed, and firefly luciferase activity was measured and normalized to Renilla luciferase.

Groups	Ki ER-α	Ki ER-β	RBA to E2 ER-α	RBA to E2 ER-β	Ratio RBA α/β	Agonist ER-α	Agonist ER-β
	nm	nm				nm	nm
E2	0.36	2.33	1	1	1	0.014	0.0942
β-LGND1	93.92	5.35	235.56	3.05	77.26	132.70	7.90
β-LGND2	39.74	2.11	112.41	1.16	96.91	38.09	1.38