High-affinity Cortisol receptor activity in the liver of the brook trout, Salvelinus fontinalis (Mitchill)

摘要: In vitro binding of [3H]cortisol to brook trout liver cytosol and salt-soluble nuclear extracts demonstrated a high affinity (cytosol association constant, Ka = (0.18 ± 0.03) × 109M−1, n = 4; extract Ka = (0.033 ± 0.01) × 109M−1, n = 4) low maximum capacity (cytosol, Nmax = 167 ± 18 fmol∙mg−1 protein, extract, Nmax = 858 ± 81 fmol∙mg−1 n = 4). Kinetics at 2 °C revealed dissociation rate constants 6.95 × 104∙M−1∙s−1 2.38 × 10−4 s−1, respectively. Gel filtration chromatography using Sephacryl S-300 as the matrix showed molecular mass for activity 319 000 ± 4486 Da Stokes' radius 6.23 ± 0.03 nm (n = 3). Competition studies with different steroids indicated considerable specificity binding. The competitive hierarchy was follows: dexamethasone > triamcinolone acetonide Cortisol corticosterone cortisone testosterone estrone ...