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. Author manuscript; available in PMC: 2021 Apr 1.
Published in final edited form as: Int J Biochem Cell Biol. 2020 Feb 2;121:105704. doi: 10.1016/j.biocel.2020.105704

Fig. 1. Proposed pivotal role of Cytc in respiration and apoptosis.

Fig. 1.

Cytc acts as an electron carrier between complex III (bc1 complex) and complex IV (cytochrome c oxidase) in the ETC resulting in efficient ATP production at complex V (ATP synthase). Under basal conditions, Cytc is phosphorylated in a tissue-specific manner. Phosphorylated Cytc is less likely to get released from the mitochondria and activate apoptosis in the cytosol. Under conditions of cellular stress, such as ischemia-reperfusion injury, dephosphorylated Cytc is eventually released from the mitochondria via channels including Bax/Bak pores. In the cytosol dephosphorylated Cytc interacts with Apaf-1 forming the apoptosome, which then activates capase-9 and the downstream caspase cascade, executing cell death. OMM; outer mitochondrial membrane, IMS; intermembrane space, IMM; inner mitochondrial membrane.