Estrogen and glucocorticoid receptors in adult canine articular cartilage.

The cytoplasmic and crude nuclear fractions of adult mongrel dog articular cartilage contained estradiol- and dexamethasone-binding components which had properties of physiologic steroid receptors. The equilibrium dissociation constants averaged 0.37 nM for estradiol and 2.27 nM for dexamethasone. The concentrations estrogen receptors ranged from below 6 to 101 fmol/mg protein in the cytosols and from below 2.8 to 17.5 fmol/micrograms DNA in the nuclear fractions. Glucocorticoid receptors were detected in only 4 of 13 cytosols (range: 61.2-132 fmol/mg protein), whereas 10 of 13 nuclear fractions contained 0.8 to 46.8 femtomoles of the receptors for each microgram of DNA. There appeared to be no marked difference between the contents of either steroid receptor in female or male dog cartilage. No receptors were detected for androgen and progesterone.