title: [3H]dexamethasone binding to plasma membrane-enriched fractions from liver of nonadrenalectomized rats.
abstract: Using liver from nonadrenalectomized adult male rats, binding sites for [3H]dexamethasone in particulate fractions are demonstrated. The binding is thermolabile, saturable, and specific for glucocorticoid. The apparent dissociation constant (Kdapp) for [3H]dexamethasone (0.48 +/- 0.084 microM) is 60-fold greater than that for cytosolic receptor (7.9 +/- 1.5 nM). The Kdapp for [3H]cortisol in particulate fractions is 2.5-fold lower than for [3H]dexamethasone (Kdapp = 0.18 microM). The binding capacities for particulate and cytosolic glucocorticoid-binding sites also differ significantly, with particulate sites at least 9.1-fold more concentrated than cytosolic sites in liver tissue. Particulate sites are determined in Percoll density gradients to have a density of 1.039 g/cc. Saturable [3H]dexamethasone radioactivity coelutes from these gradients with the plasma membrane marker enzyme 5'-nucleotidase. Adrenalectomy causes the complete loss of particulate binding sites by 6 days postadrenalectomy; however, these sites can be regenerated to two thirds of the nonadrenalectomy level by 20-30 days postadrenalectomy.
authors.affiliation: Department of Chemistry and Biochemistry, Middlebury College, Vermont 05753.
authors.forename: F W
authors.initials: FW
authors.lastname: Quelle
authors.forename: R V
authors.initials: RV
authors.lastname: Smith
authors.forename: C A
authors.initials: CA
authors.lastname: Hrycyna
authors.forename: T D
authors.initials: TD
authors.lastname: Kaliban
authors.forename: J A
authors.initials: JA
authors.lastname: Crooks
authors.forename: J M
authors.initials: JM
authors.lastname: O'Brien
mesh_terms: D000311:Adrenal Glands / Q000502:physiology*; D000315:Adrenalectomy; D000818:Animals; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D003907:Dexamethasone / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008297:Male; D011205:Povidone; D051381:Rats; D011965:Receptors, Glucocorticoid / Q000302:isolation & purification / Q000378:metabolism*; D012016:Reference Values; D012822:Silicon Dioxide; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D011965:Receptors, Glucocorticoid; C028697:dexamethasone receptor; C016039:Percoll; D012822:Silicon Dioxide; D003907:Dexamethasone; D011205:Povidone