Specific regulation by steroid hormones of the amount of type I cyclic AMP-dependent protein kinase holoenzyme.

The total amounts of type I and type II cytoplasmic cyclic AMP-dependent protein kinase activities were measured in various tissues of intact rats and rats subjected to castration, hypophysectomy, or adrenalectomy. After castration, the total amount of type I activity decreased rapidly in classifically steroid-responsive tissues such as the ventral prostate and levator ani muscle and less rapidly in the liver. After hypophysectomy and adrenalectomy, type I activity in the liver decreased to the same extent as after castration. Type I activity could be maintained in the ventral prostate and levator ani muscle at control levels by the daily injection of dihydrotestosterone. Furthermore, after post-castration regression of the prostate for 3 days, three daily subcutaneous injections of dihydrotestosterone resulted in a complete restoration of type I activity toe the intact level. The amount of type II activity was not altered by any of the experimental ablations. This study provides evidence linking steroid action to the ability of steroid-responsive tissues to maintain a substantial activity of type I cyclic AMP-dependent protein kinase.