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Published on: September 18, 2014
Bovine mitochondrial rhodanese is a phosphoprotein
1Department of Biochemistry and Biophysics, John A. Burns School of Medicine, University of Hawaii, Honolulu 96822.
The Journal of Biological Chemistry
|February 15, 1989
Summary
Mitochondrial rhodanese is phosphorylated, acting as a key enzyme in a bicyclic cascade that regulates respiration and ATP production. This phosphorylation is modulated by a cAMP-independent rhodanese kinase, influencing cellular energy demands.
Area of Science:
- Biochemistry
- Mitochondrial Function
- Enzyme Regulation
Background:
- Rhodanese, a mitochondrial sulfurtransferase, plays a role in cellular metabolism.
- Previous studies resolved rhodanese into two forms, A and B, using DEAE-Sephadex chromatography.
Purpose of the Study:
- To investigate the phosphate content of rhodanese.
- To identify the enzyme responsible for rhodanese phosphorylation.
- To propose a model for rhodanese's role in regulating mitochondrial respiration.
Main Methods:
- Phosphate analysis of rhodanese preparations.
- Chromatographic separation (DEAE-Sephadex, Sephadex G-100, Affi-Gel Blue).
- Phosphorylation assays using [gamma-32P]ATP and cAMP-dependent protein kinase.
Main Results:
- Significant protein-bound phosphate (30-40%) was found in rhodanese.
- Rhodanese A and B correspond to dephospho- and phosphorhodanese, respectively.
- A cAMP-independent rhodanese kinase activity was identified in liver extracts.
Conclusions:
- Rhodanese is regulated by phosphorylation, forming a bicyclic cascade system.
- This system modulates mitochondrial respiration and ATP production.
- Mitochondria can adapt to changing energy demands via this signaling pathway.
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