VITAMIN-D AND GONADAL STEROID-RESISTANT NEW-WORLD PRIMATE CELLS EXPRESS AN INTRACELLULAR PROTEIN WHICH COMPETES WITH THE ESTROGEN-RECEPTOR FOR BINDING TO THE ESTROGEN RESPONSE ELEMENT

New World primates (NWP) exhibit a form of compensated resistance to v itamin D and other steroid hormones, including 17 beta-estradiol. One postulated cause of resistance is that NWP cells overexpress one or mo re proteins which block hormone action by competing with hormone for i ts cognate hormone response element. Here we report that both nuclear and postnuclear extracts from NWP, but not Old World primate, cells co ntained a protein(s) capable of binding directly to the estrogen respo nse element (ERE). This ERE binding protein(s) (ERE-BP) was dissociate d from the ERE by excess of either unlabeled ERE or excess of the ERE half-site moth AGGTCAcag. DNA affinity chromatography using concatamer s of the latter resulted in > 20,000-fold purification of the ERE-BP. The intensity of the ERE-BP-ERE complex in electromobility shift assay was indirectly related to the amount of wild-type Old World primate e strogen receptor (ER) but not affected when potential ligands, includi ng 17 beta-estradiol (up to 100 nM), or anti-ER antibody was added to the binding reaction. We conclude that vitamin D-resistant and gonadal steroid-resistant NWP cells contain a protein(s) that may ''silence'' ER action by interacting directly with the ERE and interfering with E R binding.