In vitro binding of progesterone to receptors in the human endometrium and the myometrium
| Autor: | Urmila Verma, Kesho R. Laumas |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
medicine.medical_specialty
Chlormadinone Acetate In Vitro Techniques Biochemistry Genetics and Molecular Biology (miscellaneous) Endometrium Transcortin Internal medicine Progesterone receptor medicine Centrifugation Density Gradient Animals Humans Binding site Receptor Progesterone Binding Sites biology Chemistry Binding protein Norgestrel Uterus Myometrium Ligand (biochemistry) Blood proteins Endocrinology biology.protein Female Steroids Rabbits Corticosterone Receptors Progesterone Protein Binding |
| Zdroj: | Biochimica et biophysica acta. 317(2) |
| ISSN: | 0006-3002 |
| Popis: | High affinity, low capacity progesterone binding receptors have been identified in the cytosol fractions of the human endometrium and the myometrium. The endometrial and the myometrial progesterone binding proteins had sedimentation coefficients of 4.5 S and 4.1 S, respectively. Analysis of the bound steroids revealed that, along with progesterone, small amounts of its metabolites (20alpha-hydroxy-4-pregnene-3-one, 5alpha-pregnane-3,20-dione, 5alpha-pregnane-20alpha-ol-3-one) were also bound to the receptor proteins. Among the steroids studied for ligand specificity, 5alpha-pregnane-3,20-dione showed the highest competition for progesterone binding sites. Progestational steroids, like chlormadinone acetate and norgestrel, did not compete for the progesterone receptors. The endometrial and the myometrial progesterone binding receptors were thermolabile and protein in nature. The molecular weight of the endometrial progestrone binding protein was about 60,000-67,000 with a molecular (Stokes) radius of 33 A and the frictional ratio of 1.26. The myometrial progesterone binding protein had a molecular weight of 56,000-58,000 with a molecular (Stokes) radius of 31 A and a frictional ratio of 1.23. The binding of corticosterone to the myometrial cytosol was only 22-34%, whereas with progesterone it was 70-95%. A study of the immunoabsorption of the plasma proteins from the endometrial and the myometrial cytosol suggested the presence of specific progesterone binding receptors in the cytosol that were different to plasma proteins. The association constant of progesterone for the endometrial progesterone receptor was 1.9 x 10(9) M(-1) and for the myometrial progesterone receptor it was 1.4 x 10(9) M(-1), values that are higher than the association constant of progesterone for corticosteroid binding globulin, which is 7 x 10(8) M(-1). The evidence suggested that the human endometrial and the myometrial progesterone binding proteins are different to the corticosteroid-binding globulin. |
| Databáze: | OpenAIRE |
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