A kinetic study of [3H]-dexamethasone binding to chick erythrocytes

Abstract 1. 1. The chick erythrocyte has about 300 specific glucocorticoid binding sites per cell. 2. 2. The apparent dissociation constant at 20°C was 0.31 nM after 1 hr incubation and decreased to 0.12nM after 8 hr incubation. 3. 3. The association rate constant of [ 3 H]-dexamethasone binding to chick erythrocytes was higher than that reported for goat mononuclear leukocytes. 4. 4. The dissociation of [ 3 H]-dexamethasone bound to erythrocytes at 20°C consisted of two components which are similar to the values reported for goat mononuclear leukocytes.