Development of increased cytoplasmic binding of androgen in the submandibular gland of the mouse with testicular feminization.

The binding of [l ,2-3H]dihydrotestosterone by cytoplasmic extracts of submandibular glands from normal male mice and from mice carrying the X-linked gene for testicular feminization (Tfm/Y) has been studied by density gradient centrifugation and gel filtration. Androgen binding in this tissue was found exclusively in the portion of the gland that is known to contain androgen-dependent elements. No binding was demonstrated in the glands of either genotype immediately after birth, but at 2 weeks of age and after high affinity binding of the hormone was found in the glands of both male and Tfm animals. At all ages studied, the apparent dissociation constant for this binding was similar in the two genotypes (around 10 XIM), but the number of binding sites in Tfm animals at 6 and 12 weeks was S-fold higher. This difference did not appear to be the result of differential degradation during the preparation of the extracts. The observation that normal and Tfm animals have identical binding parameters at 2 weeks of age suggests: (a) that the postnatal development of androgen binding in submandibular gland is not androgen-dependent; (b) that androgen binding develops prior to the onset of sexual dimorphism of the gland; and (c) that the later development of enhanced binding of androgen by submandibular gland cytoplasm of the adult Tfm mouse is not caused by the appearance of an altered androgen binding protein but is the result of the accumulation of a physiologically normal binding protein.