Estradiol binding in rat thymus cells

Estradiol binding in preparations of female rat thymi is demonstrated by three different approaches (dextran-coated charcoal method, immunofluorescence technique and thin-layer gel filtration). Scatchard's analysis of [3H]-estradiol proves consistent with the existence of a single class of receptor sites, having a dissociation constant (Kd) of about 2 x 10(-10) M. Steroid binding specificity in the thymus is similar to that found in the uterus. On thin-layer gel filtration the binding appears in the 8S region similar to that observed for the uterus. With the immunofluorescence sandwich technique, estradiol proves to bind to a specific cytoplasmic component that subsequently migrates into the nucleus.