Evidence that the same structural gene encodes testicular and adrenal 3β-hydroxysteroid dehydrogenase-isomerase

Abstract

Thermostability of 3β-hydroxysteroid dehydrogenase-isomerase (3βHSD) activity was examined in testes and adrenal glands from several inbred lines and feral mice. A thermolabile varant of 3βHSD was detected in the feral Brno mice. The thermostability ( t 1/2 ) of 3βHSD was approximately 7 min for both testes and adrenal glands from C57BL/6J mice, compared with 4 min for both tissues from Brno mice. Comparison of testicular and adrenal 3βHSD thermostability in six kinds of mice indicated that the t 1/2 of 3βHSD was correlated in the two tissues and could be classified into two distinct types, thermolabile and thermostable. In contrast, quantitative variants in 3βHSD activity were not correlated in the two tissues. These data are consistent with the hypothesis that testicular and adrenal 3βHSD is encoded by the same structural gene but that expression of 3βHSD activity is independently controlled in testes and adrenal glands.