SUBCELLULAR-DISTRIBUTION OF DELTA-S-3-BETA-HYDROXY STEROID DEHYDROGENASE IN THE GRANULOSA-CELLS OF THE DOMESTIC-FOWL (GALLUS-DOMESTICUS)

The distribution of 3β-hydroxy steroid dehydrogenase was examined in the subcellular fractions of granulosa cell collected from the ovary of the domestic fowl. 3β-Hydroxy steroid dehydrogenase activity was observed in the mitochondrial (4000 g for 20 min) and microsomal (105000 g for 120 min) fractions. Approximately three times more 3β-hydroxy steroid dehydrogenase activity was associated with the cytochrome oxidase activity (a mitochondrial marker enzyme) in anteovulatory-follicle granulosa cells than with that of the postovulatory follicle. Comparison of the latent properties of mitochondrial 3β-hydroxy steroid dehydrogenase with those of cytochrome oxidase and isocitrate dehydrogenase indicated that 3β-hydroxy steroid dehydrogenase is located extramitochondrially. This apparent distribution of 3β-hydroxy steroid dehydrogenase is explained on the basis tht the mitochondrial activity is either an artefact caused by a redistribution in the subcellular location of the enzyme, occurring during homogenization, or by the existence of a functionally heterogeneous endoplasmic reticulum that yields particles of widely differing sedimentation properties.