Autophagy is the natural, regulated mechanism of the cell that removes unnecessary or dysfunctional components.[3] It allows the orderly degradation and recycling of cellular components.
Mitophagy is the selective degradation of mitochondria by autophagy. It often occurs to defective mitochondria following damage or stress. Mitophagy promotes turnover of mitochondria and prevents accumulation of dysfunctional mitochondria which can lead to cellular degeneration. It is mediated by Atg32 and NIX and its regulator BNIP3 in mammals. Mitophagy is regulated by PINK1 and parkin proteins. The occurrence of mitophagy is not limited to the damaged mitochondria but also involves undamaged ones.
Autophagy has roles in various cellular functions. One particular example is in yeasts, where the nutrient starvation induces a high level of autophagy. This allows unneeded proteins to be degraded and the amino acids recycled for the synthesis of proteins that are essential for survival.
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