MOTS-c breaks a rule that held for forty years: that mitochondrial DNA encodes only the handful of proteins that build the respiratory chain, plus the rRNAs and tRNAs needed to make them. MOTS-c is a 16-amino-acid peptide encoded inside a mitochondrial ribosomal-RNA gene, and under metabolic stress it travels out of the mitochondria and into the nucleus to influence gene expression. This profile covers what the molecule is, the mitochondrial-derived peptide class it belongs to, the AMPK-centered signaling the literature describes, and the handling rules for a peptide carrying two methionines and a tryptophan. It is written for laboratory reference and makes no clinical claims.
What MOTS-c is
- Sequence:
MRWQEMGYIFYPRKLR(16 amino acids) - Average mass: 2174.6 g/mol
- Name: Mitochondrial ORF of the 12S rRNA type-c.
- Origin: Encoded within the 12S ribosomal-RNA gene (MT-RNR1) of mitochondrial DNA; first characterized by Lee, Cohen, and colleagues (Cell Metabolism, 2015). The research material is synthetic.
Why is MOTS-c called a mitochondrial-derived peptide?
Because its 16-amino-acid sequence is encoded not in the nuclear genome but within the mitochondrial DNA itself — specifically inside the 12S ribosomal-RNA gene, MT-RNR1. That places it in a small class of mitochondrial-derived peptides (MDPs), alongside humanin, that overturned the long-held assumption that mtDNA encodes only the 13 respiratory-chain subunits plus its rRNAs and tRNAs.
The discovery reframed mitochondrial DNA as a source of signaling molecules, not just respiratory machinery. A handful of short open reading frames hidden in the rRNA genes produce peptides with their own biology:
| Mitochondrial-derived peptide | Encoded in | Length |
|---|---|---|
| Humanin | 16S rRNA (MT-RNR2) | 24 aa |
| MOTS-c | 12S rRNA (MT-RNR1) | 16 aa |
| SHLP1–6 | 16S rRNA (MT-RNR2) | varies |
One practical consequence follows from the mitochondrial origin: because mtDNA uses a slightly different genetic code than the nucleus, MOTS-c is described as being translated in the cytoplasm from the mitochondrial transcript, a detail that has shaped how researchers think about where the peptide is made.
From the mitochondria to the nucleus: how MOTS-c signals
The signaling story is what makes MOTS-c more than a curiosity. In the published mechanism it activates AMP-activated protein kinase (AMPK), the cell's central energy sensor, and it regulates the folate–methionine one-carbon cycle that feeds purine biosynthesis. Under metabolic stress — the literature describes glucose restriction and oxidative stress as triggers — the peptide moves from the mitochondria into the nucleus, where it influences the expression of stress-adaptive and antioxidant genes.
This mitochondria-to-nucleus communication is the conceptual hook of the mitochondrial-derived peptide field. Where a coenzyme like NAD+ is a metabolic substrate and cofactor, MOTS-c behaves as a signaling molecule that couples mitochondrial state to nuclear output.
Published research scope
The MOTS-c literature is recent and predominantly preclinical. The threads most often cited are:
- Metabolic homeostasis. The original Lee/Cohen work (Cell Metabolism, 2015) characterized AMPK activation and insulin-sensitivity readouts in rodent models and cell culture.
- Exercise and mitochondrial physiology. Subsequent work examined MOTS-c in the context of exercise response and skeletal-muscle metabolism in rodents.
- Aging-associated decline. Circulating mitochondrial-derived peptide levels have been reported to change with age, which is the observation that frames much of the current interest.
Controlled human data remain limited. Researchers should treat MOTS-c as a preclinical metabolic-signaling probe and design accordingly. As with every compound in this library, the above is summarized observationally from the peer-reviewed record and is not treatment guidance; the product is supplied strictly for laboratory research.
Stability and handling
MOTS-c is more handling-sensitive than a peptide of its size would otherwise be, and the reason is in the sequence. Two methionines (positions 1 and 6) make oxidation to methionine sulfoxide the dominant degradation route, and the single tryptophan (position 3) adds genuine photolability. There is no cysteine, so disulfide scrambling is not a concern.
- Refrigerated (2–8°C): 24 months as a sealed lyophilized vial is the standard manufacturer-published spec.
- Frozen (−20°C): 36+ months, the research-archive storage temperature.
Reconstitution and analytical notes
Reconstitution
The standard reconstitution protocol applies: stream bacteriostatic water against the glass wall, swirl gently, never shake, and refrigerate. Reconstituted and refrigerated, working stocks hold for 14–28 days; aliquot and freeze for longer studies, and keep the solution out of direct light. Our 10 mg vial pairs with bacteriostatic water for reconstitution.
HPLC and mass spectrometry
On reverse-phase HPLC MOTS-c elutes as a single dominant peak; the tryptophan and the two tyrosines make UV detection at 280 nm straightforward in addition to the standard 214 nm. On ESI-MS the expected average mass is 2174.6 g/mol. The diagnostic degradation signature to watch is a +16 Da increment per oxidized methionine — a single +16 peak indicates partial oxidation at M1 or M6, the same chemistry that produces the methionine-sulfoxide shoulder in TB-500. Confirm identity and net peptide content against the lot's report in the open CoA library; the CoA reading guide covers the cues.
Common errors to avoid:
- Leaving vials in the light. The tryptophan makes MOTS-c photolabile; cumulative bench-light exposure matters.
- Letting reconstituted material warm. Methionine oxidation accelerates above ~10°C. Refrigerate after every use.
- Reading a +16 Da peak as an impurity. It is methionine sulfoxide — an oxidation product of the molecule itself, not a contaminant.
- Shaking the vial. Like every peptide, MOTS-c aggregates at the air-water interface. Swirl only.
- Repeated freeze-thaw of one reconstituted vial. Aliquot first; thaw single portions.
Where to find primary literature
Search "MOTS-c" and "mitochondrial-derived peptide" to index the record; the foundational paper is Lee et al., Cell Metabolism, 2015, and "humanin" surfaces the related MDP literature. For the molecule's place among the other metabolic compounds in this catalog, the NAD+ profile and the GLP-3 RT profile are the adjacent references.
