Synthesis and processing of mitochondrial steroid hydroxylases. In vivo maturation of the precursor forms of cytochrome P-450scc, cytochrome P-450(11)beta, and adrenodoxin
The synthesis and maturation of the precursor forms of three mitochondrial enzymes involved in steroid hormone biosynthesis have been studied in vivo. Primary cultures of bovine adrenocortical cells were radiolabeled with (TVS) methionine and newly synthesized cholesterol side-chain cleavage cytochrome P-450 (P-450scc), 11 beta-hydroxylase cytochrome P-450 (P-450(11)beta), and adrenodoxin immunoisolated using specific antibodies. Both the precursor and mature forms of P-450scc and P-450(11)beta were detected during short periods of pulse labeling. Pulse-chase experiments showed that the precursor form of each cytochrome P-450 had an apparent half-life of 3.5 min. In contrast, the precursor form of adrenodoxin was not readily detected in pulse-labeling experiments until a substantial amount of its mature form had accumulated. The synthesis of the P-450scc and P-450(11)beta precursors was induced in cells maintained in the presence of adrenocorticotropin, and the rates of appearance of their processed forms were also increased. The mature forms of all three proteins were immunoisolated from a trypsinized mitochondrial fraction prepared from the radiolabeled cells, demonstrating that the mature proteins were localized within the organelle. These studies establish that the maturation of the precursor forms of the mitochondrial steroidogenic enzymes are characterized by steps similar to those reported for other mitochondrial precursor proteins.
- Research Organization:
- Univ. of Texas Health Science Center, Dallas
- OSTI ID:
- 6259335
- Journal Information:
- J. Biol. Chem.; (United States), Vol. 22
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HYDROXYLASES
BIOSYNTHESIS
MITOCHONDRIA
BIOCHEMISTRY
ADRENAL GLANDS
ADRENAL HORMONES
CATTLE
CYTOCHROMES
IN VIVO
KINETICS
METHIONINE
SULFUR 35
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMISTRY
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
DRUGS
ENDOCRINE GLANDS
ENZYMES
EVEN-ODD NUCLEI
GLANDS
HORMONES
ISOTOPES
LIGHT NUCLEI
LIPOTROPIC FACTORS
MAMMALS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANOIDS
ORGANS
OXIDOREDUCTASES
PIGMENTS
RADIOISOTOPES
RUMINANTS
STEROID HORMONES
SULFUR ISOTOPES
SYNTHESIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques