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ATP-dependent protease in bovine adrenal cortex. Tissue specificity, subcellular localization, and partial
The Journal of Biological Chemistry
|May 10, 1985
Summary
Mitochondrial proteolysis in bovine adrenal cortex is significantly stimulated by adenosine triphosphate (ATP) and magnesium ions (MgCl2). This ATP-dependent protease activity is located in the mitochondrial matrix and shows high specificity for ATP.
Area of Science:
- Biochemistry
- Mitochondrial Biology
- Enzymology
Background:
- Mitochondria possess proteolytic enzymes crucial for protein turnover.
- The role and regulation of mitochondrial proteases, particularly ATP-dependent ones, are not fully understood.
Purpose of the Study:
- To investigate ATP-dependent proteolytic activities within bovine adrenocortical mitochondria.
- To characterize the localization, properties, and specificity of this enzymatic activity.
Main Methods:
- Utilized [14C-methyl]casein as a substrate to measure proteolytic activity.
- Employed differential centrifugation, gel filtration chromatography, and enzyme inhibition assays.
- Investigated activity across various tissues and the effect of dexamethasone treatment on rat adrenal glands.
Main Results:
- Washed mitochondria exhibited low basal proteolytic activity, significantly stimulated (9-fold) by ATP and MgCl2 at pH 8.2.
- The ATP-dependent proteolytic activity was localized to the mitochondrial matrix.
- The solubilized protease was sensitive to various inhibitors but showed high specificity for ATP, with GTP and UTP showing partial substitution.
- Adrenal cortex demonstrated high activity, which decreased with dexamethasone-induced adrenal atrophy.
Conclusions:
- Bovine adrenocortical mitochondria possess a distinct ATP-dependent protease localized in the matrix.
- This protease exhibits specific requirements for ATP and MgCl2 and is modulated by physiological conditions like adrenal atrophy.