Specific interaction of corticosteroids with binding sites in the plasma membranes of the rat anterior pituitary gland.
The binding of glucocorticoids to a crude fraction of rat pituitary plasma membranes and to solubilized membrane proteins was measured. The binding characteristics were similar to those exhibited by transcortin: radioactive corticosterone was bound to a greater extent than radioactive dexamethasone and labelled corticosterone, but not labelled dexamethasone, was displaced by unlabelled corticosterone, deoxycorticosterone and progesterone. A Scatchard plot of the binding data revealed the presence of a binding material with a dissociation constant of about 3.2 nmol/l, which sedimented at 4S after sucrose density-gradient centrifugation. It was found that the number of binding sites was inversely related to the concentration of corticosterone in the circulation and was increased after long-term adrenalectomy. These data suggest that a material similar to transcortin is complexed to the plasma membrane of rat pituitary cells.
D000315:Adrenalectomy; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D003345:Corticosterone / Q000378:metabolism*; D003907:Dexamethasone / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D009708:Nucleotidases / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D051381:Rats; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism*; D013312:Stress, Physiological / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism
D011965:Receptors, Glucocorticoid; D011987:Receptors, Steroid; D003907:Dexamethasone; D009708:Nucleotidases; D003345:Corticosterone