ACTH stimulation on cholesterol side chain cleavage activity of adrenocortical mitochondria

1981 ◽  
Vol 36 (2) ◽  
pp. 105-122 ◽  
Author(s):  
Tokuji Kimura
Keyword(s):  
Side Chain ◽  
Acth Stimulation ◽  
Side Chain Cleavage ◽  
Cleavage Activity ◽  
Chain Cleavage

scholarly journals Interaction of human CYP17 (P-45017α, 17α-hydroxylase-17,20-lyase) with cytochrome b5: importance of the orientation of the hydrophobic domain of cytochrome b5

1997 ◽  
Vol 321 (3) ◽  
pp. 857-864 ◽  
Author(s):  
Peter LEE-ROBICHAUD ◽  
Mustak A. KADERBHAI ◽  
Naheed KADERBHAI ◽  
J. Neville WRIGHT ◽  
Muhammad AKHTAR
Keyword(s):  
Signal Sequence ◽  
Cytochrome B5 ◽  
Amino Acid Sequences ◽  
Side Chain ◽  
Hydrophobic Domain ◽  
Side Chain Cleavage ◽  
The Core ◽  
Cleavage Activity ◽  
P450 Reductase ◽  
Chain Cleavage

Human CYP17 (P-45017α, 17α-hydroxylase-17,20-lyase)-catalysed side-chain cleavage of 17α-hydroxyprogestogens into androgens is greatly dependent on the presence of cytochrome b5. The native form of cytochrome b5 is composed of a globular core, residues 1Ő98, followed by a membrane insertable C-terminal tail, residues 99Ő133. In the present study the abilities of five different forms of cytochrome b5 to support the side-chain cleavage activity of CYP17 were compared. The five derivatives were: the native pig cytochrome b5 (native pig), its genetically engineered rat counterpart (coreŐtail), the soluble core form of the latter (core), the core with the secretory signal sequence of alkaline phosphatase appended to its N-terminal (signalŐcore) and the latter containing the C-terminal tail of the native rat protein (signalŐcoreŐtail). When examined by Edman degradation and MS, the engineered proteins were shown to have the expected N-terminal amino acid sequences and molecular masses. The native pig was found to be acetylated at the N-terminal. The native pig and coreŐtail enzymes were equally efficient at enhancing the side-chain cleavage activity of human CYP17 and the signalŐcoreŐtail was 55% as efficient. The core and signalŐcore constructs were completely inactive in the aforementioned reaction. All the five derivatives were reduced to varying degrees by NADPH:cytochrome P-450 (NADPH-P450) reductase and the relative efficiencies of this reduction were reminiscent of the behaviour of these derivatives in supporting the side-chain cleavage reaction. In the side-chain cleavage assay, however, NADPH-P450 reductase was used in large excess so that the reduction of cytochrome b5 derivatives was not rate-limiting. The results highlight that productive interaction between cytochrome b5 and CYP17 is governed not only by the presence of a membrane insertable hydrophobic region on the cytochrome b5 but also by its defined spatial orientation at the C-terminal.

Critical role of the plasma membrane for expression of mammalian mitochondrial side chain cleavage activity in yeast

2003 ◽  
Vol 270 (7) ◽  
pp. 1502-1514 ◽  
Author(s):  
Catherine Duport ◽  
Barbara Schoepp ◽  
Elise Chatelain ◽  
Roberto Spagnoli ◽  
Bruno Dumas ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Critical Role ◽  
Side Chain ◽  
Side Chain Cleavage ◽  
Cleavage Activity ◽  
Chain Cleavage

scholarly journals Estrogen Stimulation of P450 Cholesterol Side-Chain Cleavage Activity in Cultures of Human Placental Syncytiotrophoblasts1

1997 ◽  
Vol 56 (1) ◽  
pp. 272-278 ◽  
Author(s):  
Jeffery S. Babischkin ◽  
Randall W. Grimes ◽  
Gerald J. Pepe ◽  
Eugene D. Albrecht
Keyword(s):  
Side Chain ◽  
Side Chain Cleavage ◽  
Cleavage Activity ◽  
Chain Cleavage ◽  
Estrogen Stimulation ◽  
Stimulation Of
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