Mitochondria are central to cellular energy production, and two peptides have become especially prominent in mitochondrial research: MOTS-c and SS-31. Both are associated with mitochondria, but they are very different molecules, with different origins and different research uses.
MOTS-c: a peptide encoded by mitochondrial DNA
MOTS-c (mitochondrial open reading frame of the 12S rRNA type-c) is a 16-amino-acid peptide first described in 2015 by researchers at the University of Southern California. What makes it unusual is its origin: it is encoded within the mitochondrial genome, in the gene for the 12S ribosomal RNA, rather than in the nuclear genome like most peptides.
Research has focused on MOTS-c as a signalling molecule between mitochondria and the rest of the cell:
- Metabolic signalling. Early studies linked MOTS-c to the folate cycle and to activation of AMPK, a key cellular energy sensor, in cell and mouse models.
- Nuclear signalling. Later work reported that under metabolic stress, MOTS-c can move into the cell nucleus and influence gene expression, which is an example of mitochondria communicating directly with the nucleus.
- Skeletal muscle. Muscle has been a major focus of MOTS-c research, including studies of how its levels change in response to physical stress in animal models.
Research compound: MOTS-c (30mg)
SS-31: a peptide that targets the inner mitochondrial membrane
SS-31, also known as elamipretide, belongs to the Szeto-Schiller family of peptides, named after the researchers Hazel Szeto and Peter Schiller. It is a synthetic tetrapeptide (D-Arg-Dmt-Lys-Phe-NH2). Its alternating positive charges and aromatic residues allow it to cross cell membranes and concentrate in the inner mitochondrial membrane.
There, SS-31 binds to cardiolipin, a phospholipid that is found almost only in the inner mitochondrial membrane and that helps organize the proteins of the electron transport chain. Research on SS-31 has examined:
- Cardiolipin binding and the structure of the inner membrane.
- Electron transport chain efficiency and the production of reactive oxygen species.
- Models of mitochondrial dysfunction in muscle, heart, kidney and other tissues.
Research compound: SS-31 (10mg)
How they compare
| MOTS-c | SS-31 | |
|---|---|---|
| Origin | Naturally encoded in mitochondrial DNA | Synthetic, designed |
| Length | 16 amino acids | 4 amino acids |
| Main research focus | Signalling between mitochondria and the cell | Inner membrane and cardiolipin |
Related reading: How to Store Lyophilized Peptides. Independent Janoshik reports are on each product page and our Lab Testing page.
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