Interaction of testosterone and testosterone receptor complexes with nuclei of skeletal muscle from intact male mice and from mice bearing the testicular feminization (Tfm) mutant gene.

With the nuclear exchange assay and the nuclear retention assay it is shown that the androgen insensitivity of Tfm mice is probably due to a defect of the nuclear acceptor sites for the testosterone receptor complex. Further on the results obtained point strongly to the possibility that hormone free androgen receptor is localized in the nuclei and in the cytoplasma according to the "equilibrium model". A practicable method for separation of unbound steroids from nuclei is described.