Cytochrome c (Cytc) plays dual roles in both life-sustaining and cellular death processes, depending on its subcellular localization. Within mitochondria, Cytc acts as a single electron carrier in the electron transport chain (ETC). When released into the cytosol after cellular stress, it triggers the assembly of the apoptosome, leading to intrinsic apoptosis. Post-translational modifications, such as phosphorylation and acetylation, strongly regulate Cytc, with six phosphorylation sites and three acetylation sites detected in vivo. These modifications influence mitochondrial respiration, membrane potential, reactive oxygen species (ROS) production, and apoptosis. Phosphorylations at T28, S47, Y48, T49, T58, and Y97 are present under basal conditions and tend to inhibit respiration, maintaining an optimal mitochondrial membrane potential (ΔΨm) to minimize ROS production. In contrast, acetylations at K8, K39, and K53 are specific to certain pathophysiological conditions. During ischemia, Cytc phosphorylations are lost, leading to ETC hyperactivity and ΔΨm hyperpolarization, resulting in exponential ROS production and reperfusion injury. However, K39 acetylation is gained during ischemia, stimulating respiration while blocking apoptosis, explaining the resilience of skeletal muscle to ischemia-reperfusion injury compared to other organs. The regulation of Cytc by these post-translational modifications highlights its critical role in maintaining mitochondrial function and cellular homeostasis.Cytochrome c (Cytc) plays dual roles in both life-sustaining and cellular death processes, depending on its subcellular localization. Within mitochondria, Cytc acts as a single electron carrier in the electron transport chain (ETC). When released into the cytosol after cellular stress, it triggers the assembly of the apoptosome, leading to intrinsic apoptosis. Post-translational modifications, such as phosphorylation and acetylation, strongly regulate Cytc, with six phosphorylation sites and three acetylation sites detected in vivo. These modifications influence mitochondrial respiration, membrane potential, reactive oxygen species (ROS) production, and apoptosis. Phosphorylations at T28, S47, Y48, T49, T58, and Y97 are present under basal conditions and tend to inhibit respiration, maintaining an optimal mitochondrial membrane potential (ΔΨm) to minimize ROS production. In contrast, acetylations at K8, K39, and K53 are specific to certain pathophysiological conditions. During ischemia, Cytc phosphorylations are lost, leading to ETC hyperactivity and ΔΨm hyperpolarization, resulting in exponential ROS production and reperfusion injury. However, K39 acetylation is gained during ischemia, stimulating respiration while blocking apoptosis, explaining the resilience of skeletal muscle to ischemia-reperfusion injury compared to other organs. The regulation of Cytc by these post-translational modifications highlights its critical role in maintaining mitochondrial function and cellular homeostasis.