For a long time it was assumed that functional proteins were encoded only in nuclear DNA. The discovery of peptides encoded by mitochondrial DNA changed that idea. MOTS-c, identified in 2015, is one of them — it is considered the first "mitokine" or mitochondrial hormone.

Research associates MOTS-c with the activation of AMPK, a regulator of cellular energy balance. In models, that pathway is linked to glucose uptake, fatty-acid oxidation and mitochondrial biogenesis. That is why it often appears in the conversation about metabolism and cellular energy.

An important nuance: to date there are no active human clinical trials for the MOTS-c peptide, and the data are preclinical. It is a compound of emerging interest, not a closed conclusion.