Localization of a Steroid 11β-Hydroxylase in the Inner Membrane Subfraction of Rat Adrenal Mitochondria¹

Steroid 11β-hydroxylation in beef adrenal cortex mitochondria. Binding affinity and capacity for specific [14C]-labeled steroids and for tritium-labeled metyrapol, an inhibitor of the 11β-hydroxylation reaction

“…In beef adrenal cortex mitochondria, only the inner mitochondrial membrane was found to bind efficiently [3H]metyrapol, as shown in Figure 2. This is in agreement with the specific location of P-450 in the inner membrane of adrenal cortex mitochondria (Yago and Ichii, 1969;Satre et al, 1969;Dodge et al, 1970; Sottocasa and Sandri, 1970). The small binding capacity of outer membrane preparations from adrenal cortex mitochondria (Figure 2) was probably due to contaminant inner mitochondrial membrane fragments.…”

Atrophy of the zona fasciculata in the adrenal cortex of thyroparathyroidectomized rats: A quantitative study

“…Decreased responsiveness might in turn be mediated through a decrease in the activity of the enzymes involved in steroidogenesis; Bouhnik et al (1973) In the present study, the decreased volume of adrenocortical mitochondria accompanied by decreased surface areas of the outerlinner mitochondrial membrane and cristae in the zona fasciculata 7 weeks after TPX, and in the zona reticularis as early as 2 weeks after TPX, correlates very closely with decreased activity of 1 ID-hydroxyluse (McCarthy and Laury, 1971;Bouhnik et al, 1973). The llp-hydroxylase is localized to the inner-membrane fraction (cristae) of adrenocortical mitochondria (Dodge et al, 1970). The significant decrease in the volume and surface area of smooth endoplasmic reticulum in the zona reticularis, and the decrease in surface area of smooth endoplasmic reticulum in the zona fasciculata at 7 weeks, correlate with the decreased 21-hydroxylase activity after TPX (Bouhnik et al, 1973).…”

Ultrastructural Characteristics of Adult Rat Adrenocortical Cells Maintained in vitro With and Without ACTH

“…The other reported modifications of dedifferentiated fasciculata elements consisted of depletion of smooth endoplasmic reticulum and great development of granular endoplasmic reticulum, changes which were also seen in our cultures. Microsomal corticosteroidogenic enzymes are believed to be situated inside the tubules of smooth endoplasmic reticulum and some studies have located enzymes like 3phydroxysteroid dehydrogenase and 2 1-hydroxylase on smooth microsomes (Inano et al 1969, Dodge et al 1970. The dramatic increase in profiles of granular endoplasmic reticulum suggests steroidogenic inactivity and the granular cisternae are probably derived from the smooth endoplasmic reticulum.…”