Specific progesterone receptors in rabbit gingiva

The cytoplasm and nucleus of male and female rabbit gingiva and cytoplasm of rabbit oral mucosa contain receptors capable of specifically binding progesterone and promegesiooe with high affinity (Kd =2.7 × 10 −9 M) and low capacity (∼10 fmol/mg protein). The binding is sensitive to heat, is destroyed by warming to 37°C for 60 min by proteolylic enzymes (pronase and trypsin), and exhibits a pattern of competition similar to that obtained with progesterone receptors from other target tissues. These results provide evidence that rabbit gingiva and buccal mucosa may function as target tissues for progestms.