Binding of ATP to the progesterone receptor.

The possible interaction of progesterone--receptor complexes with nucleotides was tested by affinity chromatography. The cytosol progesterone receptor from hen oviduct was partially purified by ammonium sulfate precipitation before use. When progesterone was bound to the receptor, the resulting complex could be selectively adsorbed onto columns of ATP-Sepharose. This interaction was reversible and of an ionic nature since it could be disrupted by high-salt conditions. A competitive binding assay was used to test the specificity of receptor binding to several other nucleotides, including ADP, AMP, and cAMP. A clear specificity for binding ATP was evident from these studies. When ATP was added to receptor preparations, the nucleotide did not affect the sedimentation properties or hormone binding characteristics of the receptor. Although the function of ATP remains unknown, these studies indicate a role of this nucleotide in some aspect of hormone receptor activity.