Linked Life Data

8274411

Source:http://linkedlifedata.com/resource/pubmed/id/8274411

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1994-2-10
pubmed:abstractText
The enzyme 3 beta-hydroxysteroid dehydrogenase isomerase (3 beta-HSD/I) is an essential step in the biosynthesis of steroid such as progesterone, mineralo- and gluco-corticoids, estrogens and androgens in steroidogenic tissues. It is considered to be mainly localized in microsomes; however, 3 beta-HSD/I activity has also been described to be associated with mitochondrial preparations. In this study, we examined the subcellular distribution of 3 beta-HSD/I in bovine adrenocortical tissue and we characterized the catalytic properties of the enzyme present in the various cell compartments. About 30% of the total 3 beta-HSD/I activity was found to remain tightly associated with the purified mitochondrial pellet. The 3 beta-HSD/I and 3-ketoreductase activities were found in microsomes as well as in mitochondria. The 3 beta-HSD/I associated with the mitochondrial fraction did not require addition of exogenous NAD+. When the pyridine nucleotide was reduced following addition of substrates of the tricarboxylic acids cycle, the mitochondrial 3 beta-HSD/I activity decreased, suggesting that the enzyme utilizes NAD+ available from the matrix space. By contrast, the microsomal enzyme was inactive in the absence of exogenous NAD+. Submitochondrial fractionation disclosed that 3 beta-HSD/I was associated (i) with the inner membrane and (ii) with a particulate fraction sedimenting in a density gradient between inner and outer membranes. This fraction was characterized as contact sites between the two membranes. 3 beta-HSD/I specific activity was much higher in this fraction than in the inner mitochondrial membrane. Altogether, these observations suggest that these mitochondrial intermembrane contact sites may represent a special organization of functional significance, facilitating both the access of cholesterol to the inner membrane where cytochrome P-450scc is located and the rapid transformation of its product, pregnenolone, to progesterone, through 3 beta-HSD/I activity.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0960-0760
pubmed:author
pubmed:issnType
Print
pubmed:volume
46
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
773-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Dual subcellular localization of the 3 beta-hydroxysteroid dehydrogenase isomerase: characterization of the mitochondrial enzyme in the bovine adrenal cortex.
pubmed:affiliation
Unité INSERM 244, DBMS/BRCE, Centre d'Etudes Nucléaires, Grenoble, France.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't