Oestrogen receptor in mammary gland cytosol of virgin, pregnant and lactating mice.
A macromolecular component binding 3H-labelled 17 beta-oestradiol in a specific manner and sedimenting in the 8-10-S region on sucrose gradient has been detected in the mammary gland cytosol of ovariectomized adult virgin mice. The dissociation constant of the macromolecule-oestradiol complex is 4.2 times 10(-10)M at 4 degrees C. The binding sites for 17beta-oestradiol of cytosol are 3.7 times 10(-14) mole/mg of protein. Incubation of cytosol with different enzymes suggests that the oestrogen-binding cytosol component is proteinaceous. The binding activity is destroyed by incubation at high temperatures and by some but not all SH-reagents tested. Competition studies show a specificity for oestrogens relative to other steroid hormones. The conclusion is that mammary gland cytosol of virgin mice contains oestradiol receptor. The receptor content does not increase in a specific manner during pregnancy and lactation but rather proportionally to total mammary gland protein.
D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D003600:Cytosol / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D007774:Lactation; D008321:Mammary Glands, Animal / Q000378:metabolism*; D051379:Mice; D008970:Molecular Weight; D011247:Pregnancy; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism; D011956:Receptors, Cell Surface
D011506:Proteins; D011956:Receptors, Cell Surface; D004958:Estradiol