There are (a) the ATP-dependent proteases, namely, the LON protease and the Clp Protease Proteolytic subunit (CLPP) and the mitochondrial AAA (ATPases Associated with diverse cellular Activities) proteases of the inner mitochondrial membrane and matrix; (b) the two ATP independent proteases, the ATP23 and HtrA2; and (c) two oligopeptidases, namely, the presequence protease (PITRM1, also known as PreP) and the mitochondrial oligopeptidase M (MEP, also known as neurolysin)  (Figure 1).
Finally, LON protease has been associated with mitochondrial DNA regulation.
Under normal conditions, ATFS-1 is imported in mitochondria and degraded by the LON protease .
On the other hand, mitophagy is enhanced by accumulation of unfolded proteins in the mitochondrial matrix or down-regulation of the LONP1 peptidase (Human LON protease homolog) [227, 228].
HIF1[alpha] binds to genomic hypoxia-responsive elements promoting the expression of a large number of genes including glycolytic enzymes and pyruvate dehydrogenase kinase-1 (PDK1 inhibits conversion of pyruvate to acetyl CoA) and it also inhibits LON protease that (among others) degrades COX4-1 subunit [62, 290, 291].
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