Effect of cAMP on the cholesterol side-chain cleavage enzyme complex (CSCC) in MA-10 Leydig tumor cell mitochondria
The rate limiting step in steroid biosynthesis is catalyzed by the cholesterol side-chain cleavage complex (CSCC) which is located on the matrix side of the inner mitochondrial membrane. It has been shown that addition of cAMP or LH/hCG to MA-10 mouse Leydig tumor cells in culture increases the production of progesterone as the major steroid. To examine the effect of cAMP on CSCC activity, cells were grown in culture flasks in the presence or absence of 10/sup -3/M cAMP for 3 h. Cells were harvested and mitochondria were isolated. Reaction conditions were optimized and contained 465000 DPM (26-/sup 14/C)cholesterol, 10mM NaCN, 0.5mM NADPH, 5mM CaCl/sub 2/, 60mM KCl and mitochondria. Reactions were stopped by the addition of ethanol and water and liberated (26-/sup 14/C)isocaproic acid was separated from uncleaved cholesterol by extraction with hexane and chloroform resulting in the retention of isocaproic acid in the aqueous layer. These experiments demonstrated a significant increase in (/sup 14/C)isocaproic acid production by mitochondria isolated from the cells grown in the presence of cAMP when compared to controls indicating that cAMP enhances the production of progesterone by increasing the activity of CSCC. Whether cAMP brings about this increase primarily through phosphorylation/dephosphorylation reactions or through some other mechanism is not clear at this time.
- Research Organization:
- Texas Tech Univ. Health Sciences Center, Lubbock
- OSTI ID:
- 7189695
- Report Number(s):
- CONF-8606151-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AMP
BIOLOGICAL EFFECTS
CHOLESTEROL
BIOSYNTHESIS
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
CLEAVAGE
ENZYME ACTIVITY
MICE
MITOCHONDRIA
NADP
PHOSPHORYLATION
PROGESTERONE
TRACER TECHNIQUES
TUMOR CELLS
ANIMAL CELLS
ANIMALS
CELL CONSTITUENTS
CHEMICAL REACTIONS
COENZYMES
CRYSTAL STRUCTURE
HORMONES
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
KETONES
KINETICS
LABELLED COMPOUNDS
MAMMALS
MICROSTRUCTURE
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANOIDS
PREGNANES
REACTION KINETICS
RODENTS
STEROID HORMONES
STEROIDS
STEROLS
SYNTHESIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques