CHARACTERIZATION OF A CYTOPLASMIC ANDROGEN RECEPTOR IN THE MALE SECONDARY SEXUAL CHARACTER OF GREEN FROG (RANA-ESCULENTA)

In the thumb pad of male Rana esculenta an androgen receptor has been demonstrated. The cytoplasmic receptor has a proteinaceous nature with a KD for testosterone of 3.12 ± 3.4 S.D. × 10-10 M and a number of sites of 333 ± 133 S.D. fmol/mg of proteins. A Stokes radius of 40 Å and a sedimentation coefficient of 3.40 ± 0.5 S.D. were determined. Using these parameters a molecular weight of ~ 57,000 and a f/f = 1.58 were calculated. Optimum binding was found at 0-10°C at pH 7.5. The [H3]-testosterone-receptor complex is focused on a pH 5-7 gradient at pH 5.4. A t 1 2 of 105min and a dissociation rate of 0.00413 min-1 for testosterone were determined. Using the nuclear exchange assay, carried out at 0-4°C. a KD of 2.85 × 10-9 M and a number of sites of 9 pmol/mg DNA were estimated for nuclear receptor. © 1979.