[Nature of steroid hormone binding to mitochondria]

Binding of 3H-corticosterone, 3H-estradiol and 3H-testosterone to the rat liver mitochondria was studied. One type of specific binding sites for corticosterone with association constant (3.25 +/- 0.51) X 10(10) M-1 and the number of binding sites (1.79 +/- +/- 0.21) X 10(-13) mol/mg of protein was found. Adrenalectomy did not change significantly corticosterone affinity to mitochondria but increased binding capacity by 70%. Binding of estradiol and testosterone was of non-specific, hydrophobic character.