Distinction between progestin- and glucocorticoid-binding sites in mammary glands. Apparent lack of cytoplasmic progesterone receptors in lactating mammary glands

Abstract

The cytosol fraction of the lactating mammary glands of mice did not appear to contain detectable amounts of progesterone receptors. Mixing experiments indicated that the absence of receptors was not due to interference by other factors in the cytosol. However, in the cytosol of mammary glands, there was specific binding of progestins to certain low-affinity sites which had characteristics of specific glucocorticoid-binding sites.