Abstract
The cytosol fraction of the oviduct uterus of laying hens was shown to possess a progesteronebinding component which preferentially bound progesterone. The dissociation constant (Kd) at equilibrium was determined as 4.38±0.24(SE)×10-10M by the use of scatchard plot, 3.77±0.20×10-10M by the use of Lineweaver-Burk plot, and 4.20±0.41×10-10M by the use of Direct-linear plot of EISENTHAL and CORNISH-BOWDEN (1974). The Kd values were different from those (5.92-6.14±×10-10M) in the plasma. The maximum number of binding sites (NBS max)/mg protein of the cytosol was 5.72±0.14×10-13mol(Scatchard), 5.33±0.28×10-13mol(Line waver-Burk), and 5.44±0, 29×10-13mol (Direct-linear), In the nuclear fraction, the binding specificity for progesterone was found, and Kd was determined as 3.12±0.07×10-10M (Scatchard), 3.03±0.10×10-10M(Lineweaver-Burk), and 3.22±0.14×10-10M (Direct-linear).The NBS max/100μg DNA was 3.85±0.05×10-14 mol (Scatchard), 3.78±0.13×10-14mol (Line weaver-Burk), and 3.88 ±0.10×10-14 mol (Direct-linear). The results suggest the presence of progesterone receptors in cytosols and of receptor-progesterone complexes in nuclear fractions of the hen oviduct uterus.
