Glucocorticoid receptors in human fetal lung

A specific dexamethasone binding protein of human fetal lung is described. Characterization of the receptor by sucrose density gradient centrifugation showed a sedimentation coefficient of approximately 7S (low ionic strength) and 4S (high ionic strength). Competition studies showed high specificity for glucocorticoids since binding of radioactive dexamethasone was inhibited by cortisol and corticosterone but not by testosterone and 17 beta-estradiol. Uptake of radioactive steroid by isolated lung nuclei required the presence of cytosol and was temperature dependent. The KCl-extractable nuclear complex sedimented at approximately 5S. Thus the dexamethasone binding components of the human fetal lung have properties similar to those described for steroid receptors present in target tissues. The concentration of receptor remained fairly constant between 15 and 28 weeks of gestation.