Specific binding sites for corticosterone in isolated cells and plasma membrane from rat liver |
| |
Authors: | Miguel Trueba Iñaki Ibarrola Kepa Ogiza Aida Marino José María Macarulla |
| |
Institution: | (1) Departmento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad del País Vasco/Euskal Herriko Unibertsitatea, 48080 Bilbao, Spain |
| |
Abstract: | Summary The specific binding of 3H]corticosterone to hepatocytes is a nonsaturable, reversible and temperature-dependent process. The binding to liver purified plasma membrane fraction is also specific, reversible and temperature dependent but it is saturable. Two types of independent and equivalent binding sites have been determined from hepatocytes. One of them has high affinity and low binding capacity (K
D=8.8nm andB
max=1477 fmol/mg protein) and the other one has low affinity and high binding capacity (K
D=91nm andB
max=9015 fmol/mg). In plasma membrane only one type of binding site has been characterized (K
D=11.2nm andB
max=1982 fmol/mg). As it can be deduced from displacement data obtained in hepatocytes and plasma membrane the high affinity binding sites are different from the glucocorticoid, progesterone nuclear receptors and the Na+,K+-ATPase digitalis receptor. Probably it is of the same nature that the one determinate for 3H]cortisol and 3H]corticosterone in mouse liver plasma membrane. Beta-and alpha-adrenergic antagonists as propranolol and phentolamine did not affect 3H]corticosterone binding to hepatocytes and plasma membranes; therefore, these binding sites are independent of adrenergic receptors. The binding sites in hepatocytes and plasma membranes are not exclusive for corticosterone but other steroids are also bound with very different affinities. |
| |
Keywords: | corticosterone hepatocytes liver plasma membranes specific binding sites glucocorticoids steroids receptors |
本文献已被 SpringerLink 等数据库收录! |