Mitochondrial organization and Ca²⁺ uptake

Mitochondria may function as multiple separate organelles or as a single electrically coupled continuum to modulate changes in [Ca²⁺]_c (cytoplasmic Ca²⁺ concentration) in various cell types. Mitochondria may also be tethered to the internal Ca²⁺ store or plasma membrane in particular parts of cells to facilitate the organelles modulation of local and global [Ca²⁺]_c increases. Differences in the organization and positioning contributes significantly to the at times apparently contradictory reports on the way mitochondria modulate [Ca²⁺]_c signals. In the present paper, we review the organization of mitochondria and the organelles role in Ca²⁺ signalling.