Evidence for the presence of specific binding sites for corticoids in mouse liver plasma membranes.
The specific binding of [3H]cortisol to plasma membranes purified from mouse liver, studied by the ultrafiltration method, shows the existence of specific binding sites for cortisol. The kinetic parameters of this binding are KD = 4.4 nM and Bmax = 685 fmol/mg protein in presence of 1 microM of corticosterone. With respect to the binding of 4 nM [3H]cortisol to the membrane, the affinities of the steroids decreased in the following order: deoxycorticosterone greater than corticosterone greater than progesterone greater than cortisol greater than prednisolone greater than testosterone greater than 20 beta-hydroxyprogesterone greater than cortisone. Estradiol, dexamethasone, ouabain and triamcinolone acetonide do not have affinity for this binding site. Neither Ca2+ nor Mg2+ affected the binding of [3H]cortisol to the plasma membranes. Likewise, the presence of agonists and antagonists of alpha and beta-adrenergic receptors did not modify the binding of [3H]cortisol. The results suggest that the plasma membrane binding site characterized is more specific for corticoids and is different from nuclear glucocorticoid and progesterone receptors.
Trueba
M
M
Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bilbao, Spain.
Vallejo
A I
AI
Rodriguez
I
I
Ibarrola
I
I
Sancho
M J
MJ
Marino
A
A
Macarulla
J M
JM
D000305:Adrenal Cortex Hormones / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002021:Buffers; D002412:Cations / Q000494:pharmacology; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D006854:Hydrocortisone / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009994:Osmolar Concentration; D013696:Temperature
D000305:Adrenal Cortex Hormones; D002021:Buffers; D002412:Cations; D006854:Hydrocortisone