Cytosol oestrogen receptor of lactating mammary gland. Effect of heparin on the aggregation of the receptor and interaction of the receptor with heparin-Sepharose.
1. An oestrogen receptor is present in low-salt cytosol of the mammary gland of lactating mice as a large aggregate; it is excluded from gel matrix when filtered on a Sephadex G-200 column and sediments at 7S in sucrose gradients. After incubation of cytosol with heparin, the receptor is dissociated. On a Sephadex G-200 column, it is included in the gel matrix and eluted as a protein with mol.wt. 260000 and a Stokes radius of 6.8nm; it sediments at 6S in sucrose gradients. 2. Dissociation of the mammary-gland cytosol oestrogen receptor seems to be the result of interaction of the oestrogen-receptor complex with heparin. This receptor interacts with heparin covalently bound to Sepharose, thereafter sedimenting at 6S. By using this interaction, the cytosol receptor was purified 200-fold compared with the homogenate, with a yield of 70%. 3. The cytosol receptor that was not incubated or was incubated with heparin was much smaller during sucrose-gradient centrifugation than during gel filtration. This discrepancy can be explained by pressure-induced dissociation during high-speed centrifugation. This possibility is supported by the decrease in the sedimentation coefficient of the receptor with increased duration of centrifugation.
D000818:Animals; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006493:Heparin / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D007774:Lactation; D046911:Macromolecular Substances; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D011247:Pregnancy; D011960:Receptors, Estrogen / Q000187:drug effects* / Q000378:metabolism; D012685:Sepharose / Q000378:metabolism
D046911:Macromolecular Substances; D011960:Receptors, Estrogen; D006493:Heparin; D012685:Sepharose