What is MOTS-c? The mitochondrial-encoded peptide in published research

Where does MOTS-c come from?

Most proteins in a human cell are encoded by nuclear DNA. Mitochondria carry their own small genome, which was long thought to encode only 13 proteins plus the RNA needed to make them. The discovery of humanin, a peptide encoded by a short open reading frame in the mitochondrial 16S rRNA gene, suggested that more such peptides could exist. In 2015, Lee and colleagues reported a second one: a short open reading frame inside the mitochondrial 12S rRNA gene that encodes a 16 amino acid peptide, which they named MOTS-c.

The published sequence is MRWQEMGYIFYPRKLR, and the calculated molecular weight is about 2,175 g/mol. Reviews describe MOTS-c as present in several tissues and in plasma, and one 2023 review summarised reports that circulating levels were lower in older people. Because the sequence sits in mitochondrial DNA, researchers describe MOTS-c as a way for mitochondria to send signals to the rest of the cell, rather than only receiving instructions from the nucleus.

How is it described at the molecular level?

In the 2015 paper, the primary target organ in mice appeared to be skeletal muscle. In cells, MOTS-c inhibited the folate cycle and the de novo purine synthesis tied to it. That led to a build up of AICAR, an intermediate that activates AMPK, the enzyme that senses cellular energy status. The authors described this folate to AMPK route as the central mechanism behind the metabolic effects they observed.

A 2018 study added a second layer. Under metabolic stress such as glucose restriction, MOTS-c moved from the cytoplasm into the nucleus in an AMPK dependent way. In the nucleus it influenced a broad set of genes, including genes with antioxidant response elements, and it interacted with stress responsive transcription factors such as NRF2. The authors presented this as evidence that a mitochondrial-encoded factor can regulate the nuclear genome directly.

What has been observed in published research?

• Diet-induced obesity and insulin resistance (mouse): in the founding study, mice given MOTS-c did not develop the insulin resistance seen with age or with a high fat diet, and diet-induced weight gain was reduced.
• Physical capacity with age (mouse): a 2021 study reported better physical performance in young (2 months), middle aged (12 months) and old (22 months) mice given MOTS-c. Intermittent administration started at 23.5 months was associated with greater physical capacity late in life.
• Exercise in humans (observational): the same 2021 study reported that exercise raised MOTS-c in human skeletal muscle and in circulation. Volunteers exercised; they were not given the peptide.
• Immobilisation muscle atrophy (mouse): in a 2024 study, a cast reduced muscle mass by about 15 percent in control mice and about 5 percent in mice given MOTS-c, with lower circulating IL-1beta and IL-6 and less lipid infiltration in muscle.
• Gestational diabetes (mouse): in a model built from a high fat diet and streptozotocin, MOTS-c given during pregnancy was associated with lower blood glucose, better insulin and glucose tolerance and fewer losses of offspring.
• Human plasma levels (observational): in a study of 10 lean and 10 obese volunteers, plasma MOTS-c was similar between groups, but it correlated with markers of insulin resistance in lean individuals only.

What the evidence does not establish

Every intervention study above was performed in mice or in cultured cells. The human studies measured how much MOTS-c was already in the blood or how it changed with exercise, which does not show what happens when the peptide is given. Results in mouse models of obesity, ageing and diabetes cannot be carried over to people without controlled trials, and none have been published for MOTS-c itself.

The mechanism is also still being mapped. The folate cycle, AMPK and nuclear translocation findings come mainly from one research group and its collaborators, and reviews describe open questions about receptors, uptake into cells and how stable the peptide is in circulation. The observational data are small: the lean versus obese plasma study had 20 participants in total.

How does MOTS-c compare with related compounds?

MOTS-c is often grouped with SS-31 because both are studied in mitochondrial research, but the two are very different. SS-31 is a synthetic tetrapeptide that binds cardiolipin in the inner mitochondrial membrane and has been through randomised human trials, including the phase 3 MMPOWER-3 trial, which did not meet its primary endpoints. MOTS-c is a natural peptide encoded by mitochondrial DNA, studied as a metabolic signal, and its intervention data come from mice. The SS-31 vs MOTS-c guide compares them in a table.

NAD+ is another molecule studied in the same area of metabolism and ageing research. It is not a peptide but a coenzyme, and it overlaps with MOTS-c through the shared theme of cellular energy sensing: MOTS-c was reported to activate AMPK, while NAD+ is consumed by sirtuins, which respond to the energy state of the cell. No published study has examined MOTS-c and NAD+ together, so any link between them in a study design is a hypothesis rather than a finding.

Which formats does Vitality Peps supply?

Vitality Peps supplies MOTS-c as a 40 mg lyophilised vial for laboratory research, documented by a batch certificate of analysis. Bacteriostatic water is listed separately as a reconstitution supply. Researchers comparing mitochondrial peptides often also review SS-31 (elamipretide), which Vitality Peps lists as a 10 mg vial.

How is it handled in the laboratory?

Lyophilised MOTS-c is stored cold and protected from light. Before use it is brought to room temperature and reconstituted with bacteriostatic water, run gently down the inside of the vial rather than onto the powder. The working concentration is calculated from the actual mass stated on the batch certificate, not the label alone. Reconstituted solution is kept refrigerated, labelled and dated. The reconstitution and storage guides explain each step.

Research use only

MOTS-c supplied by Vitality Peps is for in vitro laboratory research only. Not a medicine, not a supplement, not for human or veterinary consumption. Nothing above is instructions for use.