Concerning the subcellular distribution of 3beta-hydroxysteroid dehydrogenase/isomerase in the rat adrenal

The distribution of 3beta-hydroxysteroid dehydrogenase/isomerase in the subcellular fractions of rat adrenal gland has been determined. Based on the total activity found, 55% was in the microsomal fraction, 10% in the heavy-mitochondrial fraction, 3% in the light-mitochondrial fraction and 26% in the fraction consisting of cell-debris plus nuclei. Ninety-five percent of the total activity was recovered in the fractions. Approximately half the activity in the heavy-mitochondrial fraction could be accounted for by microsomal contamination.