The role of Mg2+ in the regulation of the structural and functional steady-states in rat liver mitochondria.
A possible relationship between mitochondrial Mg2+ levels, structural configurations, and functional steady states has been studied in rat liver mitochondria. The results show that the concentration of mitochondrial Mg2+ in respiratory state 4 is definitely higher than in respiratory state 3. The metabolic transition from state 3 to state 4 and vice-versa is associated with reversible influx-efflux of about 10 nmol of Mg2+ per mg protein. The net uptake of this aliquot of Mg2+ is a necessary condition in order for the metabolic transition to state 4, both structurally and functionally, to occur. This process requires a threshold concentration of external Mg2+ greater than 5 mM. The phosphorylative mechanism does not appear to depend on the presence or absence of external Mg2+. The role of Mg2+ on the attainment and maintenance of the structural and functional steady state 4 seems to be correlated with its regulatory effect on the concentration of the mitochondrial P(i).
Masini
A
A
Institute of Biological Chemistry, University of Modena, 41100 Modena, Italy.
Ceccarelli-Stanzani
D
D
Muscatello
U
U
D000818:Animals; D004734:Energy Metabolism / Q000187:drug effects; D066298:In Vitro Techniques; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism* / Q000494:pharmacology; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats
D010710:Phosphates; D008274:Magnesium