ウサギ子宮Progestogen Receptor第2報-ステロイド特異性-

概要

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Steroid specificity of progestogen receptor in rabbit uterine cytosol was studied. 3H-progesterone was incubated with the uterine 274,000 G supernatant of white female rabbits for 4 hrs. at 4°C with and without cold steroid. Free and non-specifically bound 3H-progesterone was removed by dextran coated charcoal. The specific binding of 3H-progesterone was inhibited by cold steroids depending on its ability to bind with the receptor. It might be concluded from the results summerized in Table 1 that, although many portions of the steroid molecule could relate to the binding affinity, 3-ketone, 20-ketone and 17β-hydroxyl group of steroids are of special importance in the binding forces. As a rule, binding affinity was well and paralleled to the biological activity. However, two biologically inactive compounds, 5α-pregnane-3, 20-dione and 17α-ethynyl-5α-estrane-7β-ol-3-one, had marked affinity to progesterone receptor. This finding was further confirmed from the observation that the 8S binding peak of progesterone in the sucrose density gradient, which representeed the progesterone receptor complex, was markedly supressed by adding either of these two compounds. Discrepancies between the binding affinity and biological effectiveness were explained on the basis of the rapid metabolism of these compounds in vivo.
日本内分泌学会の論文