Release of Ca2+ and Mg2+ from yeast mitochondria is stimulated by increased ionic strength.

摘要: Divalent cations are required for many essential functions of mitochondrial metabolism. Yet the transporters that mediate flux these molecules into and out mitochondrion remain largely unknown. Previous studies in yeast have led to molecular identification a component major electrophoretic Mg2+ uptake system this organism as well functional mammalian homolog. Other characterization an equilibrative fatty acid-stimulated Ca2+ transport activity. To gain deeper understanding regulation divalent cation levels we further characterized efflux from mitochondria. When isolated mitochondria Saccharomyces cerevisiae were suspended salt-based suspension medium, released matrix space. Release did not spontaneously occur non-ionic mannitol media. energized medium presence they able accumulate by addition electrogenic ionophore ETH-129. However, KCl or choline Cl under same conditions, unable retain was taken up due activation pathway, although substantial membrane potential driving maintained. This independent acids, which previously been shown activate transport. Endogenous also when ionic but retained upon acid addition. metal chelators Mg2+, supporting existence external cation-binding site regulating release. Matrix space slowly Ca2+, respiratory substrates, increasing pH, nucleotides ATP, ADP, GTP, ATP-gamma-S. In release activated increased strength. Free nucleotides, ion chelators, pH stimulated cells is likely important mechanism concentrations.