The Basic Characteristics of Low-affinity Glucocorticoid Binding Sites / 第二军医大学学报

ABSTRACT

Scatchard, pseudoscatchard and competitive analyses showed that there were two glucocorticoid (GC) binding sites in rat hepatic cytosol high-affinity glucocorticoid binding sites (HAGS) and low-affinity glucocorticoid binding sites (LAGS). Pseudoscatchard analysis showed the dissociation constant (Kd) of LAGS was 4.1+1.4umol/L (n=4). The inactivation of LAGS in vitro was slower" than that of HAGS. LAGS and HAGS could not be separated by DEAE-cellulose chfomatography. HAGS were saturable and had steroid specificity for glucocorticoid just as the classic glucocorticoid receptor. Triamcinolone acetonide, RU486 and RU26988 competed equally well to LAGS while aldosterone, progesterone, estradiol and testosterone did not compete with LAGS. These results suggest that LAGS have steroid specificity for glucocorticoids. The biological actions of LAGS await fur ther study.