Abstract
3H-Dexamethasone (Dex)-receptor complexes prepared from the rat liver cytosol efficiently bound to the nuclear matrix from the same tissue. The binding was increased with the concentration of the 3H-Dex-receptor complex added and reached a maximum plateau. However, when the partially purified 3H-Dex-receptor complex was used, saturation of the binding sites in the nuclear matrix was not observed in the range of concentration of 3H-Dex-receptor complex used. Therefore, it was considered that the apparent saturability observed in the binding of the unpurified receptor complexes is caused by the translocation inhibitor (s) in the cytosol. When the binding capacity was expressed on the basis of unit weight of DNA, the nuclear matrix exhibited 20 times more of that the unfractionated nuclei. However, no line of evidence of enrichment of the binding sites in the DNA isolated from the nuclear matrix was observed. These observations show that the role of the nuclear matrix in the action of glucocorticoid is quite uncertain.
