Some characteristics of Ca2+ transport in plant mitochondria.
Coupled mitochondria isolated from the white leaves of cabbage (Brassica Oleracea, var. capitata) were inactive in respiration-coupled Ca2+ accumulation, in contrast to mitochondria isolated from etiolated corn (Zea mays) which showed the ability to take up Ca2+ from the medium, although with a much lower activity than liver mitochondria. The addition of corn mitochondria to aerobic medium containing succinate as respiratory substrate and a free Ca2+ concentration of 40 microM resulted in Ca2+ uptake with a decrease in free Ca2+ concentration until a steady state of about 2.0 microM was reached and maintained constant for several minutes. Perturbation of this steady state by the addition of Ca2+ or EGTA was followed by Ca2+ uptake or release, respectively, until the steady state was attained at the original extramitochondrial free Ca2+ concentration. These results indicate that corn but not cabbage mitochondria, as with some animal mitochondria, have the ability to buffer external Ca2+ and may be involved in the maintenance of Ca2+ homeostasis in the cell.
D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000378:metabolism; D010101:Oxygen Consumption; D010944:Plants / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats
D002118:Calcium