The Role of the Mitochondrial Apoptosis Induced Channel MAC in Cytochrome c Release
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Permeabilization of the mitochondrial outer membrane is a crucial event during apoptosis. It allows the release of proapoptotic factors, like cytochrome c, from the intermembrane space, and represents the commitment step in apoptosis. The mitochondrial apoptosis-induced channel, MAC, is a high-conductance channel that forms during early apoptosis and is the putative cytochrome c release channel. Unlike activation of the permeability transition pore, MAC formation occurs without loss of outer membrane integrity and depolarization. The single channel behavior and pharmacology of reconstituted MAC has been characterized with patch-clamp techniques. Furthermore, MAC’s activity is compared to that detected in mitochondria inside the cells at the time cytochrome c is released. Finally, the regulation of MAC by the Bcl-2 family proteins and insights concerning its molecular composition are also discussed.
KeywordsMitochondrial apoptosis-induced channel MAC patch clamp cytochrome c Bax
Mitochondrial apoptosis-induced channel
Permeability transition pore
Translocase of the outer membrane
Voltage-dependent anion-selective channel
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