Mitochondrial calcium channels.

Mitochondrial Ca(2+) handling plays an important role in energy production and various cellular signaling processes. Mitochondrial Ca(2+) uptake is regulated by the mitochondrial Ca(2+) uniporter (MCU), at least one non-MCU Ca(2+) channel and possibly a mitochondrial ryanodine receptor. Two distinct mechanisms mediate Ca(2+) outward transport, the Na(+)-dependent (mNCX) and the Na(+)-independent Ca(2+) efflux. In recent years we gained more insight into the regulation and function of these different Ca(2+) transport mechanisms. However, the precise physiological role and the molecular structure of all mitochondrial Ca(2+) transporters and channels still has to be determined.