What it is
MOTS-c is a small peptide, just 16 amino acids long.
It is not made by the cell nucleus, the way almost all of our proteins are. It is encoded by the mitochondrion itself — the cell's power plant.
It is, quite literally, a message the mitochondria send to the rest of the body.
The technical detail
A mitochondrial-derived peptide (MDP), encoded within the 12S rRNA gene of mitochondrial DNA.

