MOTS-c — short for “Mitochondrial Open-reading-frame of the Twelve-S rRNA type-c” — occupies an unusual place in peptide biology. It is one of a small family of mitochondrial-derived peptides (MDPs): short peptides encoded not in the nuclear genome but within the mitochondrial DNA itself, in a region of the 12S ribosomal RNA gene that was not previously known to encode a functional peptide. For laboratories modeling cellular energy metabolism, AMPK signaling, mitochondrial-to-nuclear communication, and the biology of aging, MOTS-c has become a compound of intense interest since its description in 2015, precisely because it links a discrete molecular sequence to a well-defined metabolic signaling pathway.
This guide is written for qualified laboratory researchers sourcing MOTS-c as a research compound. It covers the molecular profile, the mechanism at the pathway and enzyme level as described in the published literature, representative preclinical and in-vitro research data, real citations you can verify yourself through PubMed, and how to evaluate the analytical documentation that should accompany a peptide of this size and complexity.
For in-vitro and preclinical laboratory research use only. Not for human consumption. Not for veterinary use.
Section 1 — Molecular Profile
MOTS-c is a mid-length linear peptide whose two methionine and no cysteine-pair architecture — the sulfur atoms come from methionine residues — gives it a characteristic mass signature.
- Compound name: MOTS-c (mitochondrial-derived peptide; 12S rRNA-encoded)
- CAS number: 1627580-64-6
- Molecular formula: C₁₀₁H₁₅₂N₂₈O₂₂S₂
- Molecular weight: ≈ 2,174.6 g/mol
- Sequence: Met-Arg-Trp-Gln-Glu-Met-Gly-Tyr-Ile-Phe-Tyr-Pro-Arg-Lys-Leu-Arg (MRWQEMGYIFYPRKLR)
- Length: 16 amino acids
- Class: Mitochondrial-derived peptide (MDP)
- Appearance: White lyophilized powder; reconstituted in aqueous buffer for in-vitro work
MOTS-c was identified by the Pinchas Cohen laboratory at the University of Southern California through computational analysis of the mitochondrial 12S rRNA gene, which revealed a short open reading frame encoding a conserved 16-residue peptide. Its mitochondrial origin is the single most distinctive feature of the molecule: unlike the overwhelming majority of peptides studied in the laboratory, MOTS-c is transcribed from the mitochondrial genome rather than the nucleus, making it a member of a class of signaling molecules that carry information outward from the mitochondrion.
At roughly 2,175 g/mol, MOTS-c is substantially larger than short bioregulator tetrapeptides, and its sequence contains four basic residues (three arginines and one lysine) plus aromatic tryptophan, tyrosine, and phenylalanine residues. This composition gives it a distinct behavior on reversed-phase HPLC and a clear protonated-molecule envelope on positive-mode LC-MS. Because the molecule contains two methionine residues, oxidation of methionine to methionine sulfoxide (+16 Da) is a common and detectable modification that a well-resolved analytical method should separate — one of the specific quality endpoints a competent laboratory checks for on a peptide of this class.
Section 2 — Mechanism (Pathway Language)
MOTS-c is studied primarily for its interaction with cellular energy-sensing pathways, chiefly AMP-activated protein kinase (AMPK), and for its capacity to translocate from the mitochondrion to the nucleus. The published mechanistic literature describes it at the enzyme, pathway, and gene-expression level, not at the level of any clinical endpoint.
The AMPK energy-sensing pathway. AMPK is a central cellular energy sensor that becomes active when the ratio of AMP to ATP rises — the biochemical signature of energy stress. In the MOTS-c literature, the peptide is studied for its capacity to activate AMPK, and the proposed upstream route runs through folate-dependent one-carbon metabolism: MOTS-c is described as modulating the folate cycle and the accumulation of the AMPK-activating metabolite AICAR (5-aminoimidazole-4-carboxamide ribonucleotide), thereby engaging the folate–AICAR–AMPK axis. Downstream of AMPK, the pathway is associated with glucose-uptake regulation, fatty-acid oxidation, and mitochondrial biogenesis at the cellular level.
Mitochondrial-to-nuclear retrograde signaling. The second defining mechanistic feature of MOTS-c is nuclear translocation. Under conditions of metabolic stress — such as glucose restriction or oxidative challenge — MOTS-c has been reported to move from the cytosol into the nucleus in an AMPK-dependent manner, where it associates with stress-responsive transcription factors and regulatory DNA elements. In the nucleus it is described as influencing genes bearing antioxidant response elements (ARE) and interacting with the NRF2 (NFE2L2) antioxidant-response pathway. This positions MOTS-c as a proposed retrograde signal — a molecule that carries information about mitochondrial energy state to the nuclear gene-expression machinery.
Exercise-responsive expression. MOTS-c expression in skeletal muscle and circulation is described in the literature as responsive to metabolic demand, with endogenous levels reported to change in association with physical activity in preclinical systems. This has made it a compound of interest in models of skeletal-muscle bioenergetics and the PGC-1α/AMPK regulatory axis.
In accordance with research-context framing, this article describes MOTS-c strictly at the enzyme, pathway, and gene-expression level. It is studied for its interaction with AMPK signaling, the folate one-carbon cycle, and nuclear stress-response pathways in controlled systems; no human outcome, therapeutic, or physiological benefit is claimed or implied.
Section 3 — Preclinical & In-Vitro Research Data
The MOTS-c literature spans cell culture, rodent metabolic and aging models, and mechanistic molecular biology.
In-vitro AMPK activation and metabolic signaling. The foundational cell-culture work reported that MOTS-c treatment activated AMPK and influenced glucose-utilization pathways in cultured cells, with the folate–AICAR–AMPK axis proposed as the upstream mechanism. This established MOTS-c as a candidate metabolic-signaling peptide and framed the subsequent mechanistic program.
Preclinical rodent metabolic models. In rodent studies, MOTS-c administration has been examined against markers of glucose handling and metabolic homeostasis. Published results in mouse models reported effects on insulin-sensitivity markers and glucose tolerance, and on diet-induced metabolic dysfunction endpoints, consistent with the AMPK-pathway mechanism characterized in cell culture. These are preclinical, animal-model findings that characterize the compound’s behavior in controlled research systems; they do not constitute evidence of any human outcome.
Nuclear translocation under metabolic stress. A distinct line of mechanistic work demonstrated that, following glucose restriction, MOTS-c translocates to the nucleus in an AMPK-dependent manner and regulates a broad set of stress-adaptation genes, including ARE-bearing antioxidant genes, via interaction with NRF2 and related transcription factors. This work provided the molecular basis for describing MOTS-c as a mitochondrial-to-nuclear retrograde signal.
Mouse and cultured-cell experiments in the 2021 study. Reynolds and colleagues examined administered MOTS-c in mouse models and stress-adaptation endpoints in cultured C2C12 cells. The paper also includes separate observations of endogenous MOTS-c expression in human samples. Those observations do not establish an effect from administering a supplied research compound to people. This guide discusses the mouse and cultured-cell experiments only. Read the 2021 primary study.
Across these studies, the recurring experimental thread is a measurable molecular endpoint — AMPK phosphorylation state, glucose-utilization markers, nuclear gene-expression profiles, or muscle-bioenergetic readouts — quantified in a defined cell or animal system.
2026 update: pathway dependence is not the same as activation
Gudiksen and colleagues (2026) examined muscle mitochondrial respiration using mouse models lacking muscle PGC-1α or both AMPKα1 and AMPKα2. Several respiratory responses observed in control muscle were absent with PGC-1α loss or attenuated with AMPK loss; the pattern varied by endpoint.
A pathway can be required without a consistent activation signal at the sampled times. AMPK Thr172 phosphorylation did not consistently increase across the mouse experiments. The authors proposed intermittent activation as a possible explanation, not a directly demonstrated time course.
This note covers the paper’s mouse mechanistic experiments, not its separate human exercise observations. The amount of MOTS-c reaching muscle cells was not established, and effects originating in other organs could complicate interpretation. These findings do not establish human outcomes or demonstrate the properties of a PYXAX product. Read the 2026 primary study.
Section 4 — Published Literature (Verifiable Citations)
The following are real, published references retrievable through PubMed and PubMed Central (PMC). Researchers are encouraged to read the primary sources directly.
- Lee C, Zeng J, Drew BG, Sallam T, Martin-Montalvo A, Wan J, Kim S-J, Mehta H, Hevener AL, de Cabo R, Cohen P. “The Mitochondrial-Derived Peptide MOTS-c Promotes Metabolic Homeostasis and Reduces Obesity and Insulin Resistance.” Cell Metabolism. 2015;21(3):443–454. PubMed: 25738459 — the foundational discovery and metabolic-signaling paper.
- Kim KH, Son JM, Benayoun BA, Lee C. “The Mitochondrial-Encoded Peptide MOTS-c Translocates to the Nucleus to Regulate Nuclear Gene Expression in Response to Metabolic Stress.” Cell Metabolism. 2018;28(3):516–524.e7. PubMed: 29983246 — nuclear-translocation and NRF2/ARE gene-regulation mechanism.
- Reynolds JC, Lai RW, Woodhead JST, et al. “MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis.” Nature Communications. 2021;12(1):470. PubMed: 33473109 — exercise-responsive expression and preclinical physical-capacity study across age groups.
- Wan W, Zhang L, Lin Y, et al. “Mitochondria-derived peptide MOTS-c: effects and mechanisms related to stress, metabolism and aging.” Journal of Translational Medicine. 2023. PMC: PMC9854231 — comprehensive review of the MOTS-c mechanistic and preclinical literature.
- Gudiksen A, et al. (2026): PGC-1α/AMPK dependence in muscle bioenergetics. Free Radical Biology and Medicine. 246:682–696. PubMed: 41520850 · DOI: 10.1016/j.freeradbiomed.2026.01.002. The mechanistic update above addresses the mouse experiments; the paper also reports separate human exercise observations.
Citing real primary literature is a core part of the PYXAX research-context standard. Any source — vendor or publication — that references “studies” without traceable identifiers should be treated with caution. Because MOTS-c is a relatively young research target (first described in 2015), the strongest evidentiary practice is to read the primary Cell Metabolism and Nature Communications reports directly and to weigh independently replicated mechanistic findings most heavily.
Section 5 — Research Applications (In-Vitro Use Cases)
Within qualified laboratory settings, MOTS-c is used as a reference and probe compound in several categories of in-vitro and preclinical work:
- AMPK-signaling assays — as a reference agonist in studies of AMPK phosphorylation and downstream metabolic-enzyme regulation in cultured cells.
- Mitochondrial-bioenergetics research — as a probe in respirometry and mitochondrial-function assays examining oxidative phosphorylation and mitochondrial biogenesis endpoints.
- Retrograde-signaling studies — as a model molecule for investigating mitochondrial-to-nuclear communication and stress-induced nuclear translocation.
- Antioxidant-response (NRF2/ARE) research — as a test agent in reporter-based studies of ARE-driven gene expression under metabolic and oxidative stress.
- Skeletal-muscle and PGC-1α models — as a comparator in cell and tissue systems studying activity-responsive metabolic gene programs.
- Analytical method development — as a defined 16-residue, methionine-containing peptide standard for validating reversed-phase HPLC and LC-MS identity and oxidation-monitoring methods.
Each of these applications is an in-vitro or preclinical research use. Compounds supplied for research are not intended for, and must not be used in, any human or veterinary context.
Section 6 — How to Evaluate a Source
MOTS-c is more complex to characterize than a short tetrapeptide, which makes analytical documentation more — not less — important. The following steps separate verifiable sourcing from marketing claims.
Step 1 — Confirm the testing laboratory is named. “Third-party tested” is meaningless without a named, accredited laboratory. Look for an ISO 17025-accredited facility or equivalent recognized accreditation, and a COA that names the lab that tested the specific batch.
Step 2 — Confirm identity by mass spectrometry. A genuine MOTS-c sample should present a protonated-molecule envelope consistent with a ~2,174.6 g/mol 16-residue peptide on LC-MS. Because MOTS-c carries multiple basic residues, expect a multiply-charged ion series; a COA that reports only “purity” without an identity mass is incomplete.
Step 3 — Confirm chromatographic purity and check for methionine oxidation. HPLC should show a single dominant peak. For a methionine-containing peptide like MOTS-c, a +16 Da oxidation product is a common, detectable impurity; a well-resolved method and an accompanying mass spectrum will reveal it.
Step 4 — Verify lot specificity. The batch number on the COA must match the vial label, and the COA date should correspond to the production lot — not a single historical testing event applied across an entire catalog.
Step 5 — Check independent verification and a complete panel. A COA you can verify without contacting the vendor — through a QR-linked laboratory portal or a searchable community database — is independent. For cell-based metabolic and signaling work, purity and identity should be accompanied by endotoxin and heavy-metal data, both of which can confound sensitive assay systems.
Section 7 — Regulatory Context (July 2026)
The FDA’s archived materials for the July 23–24, 2026 Pharmacy Compounding Advisory Committee meeting include MOTS-c-related bulk substances. This is a historical reference, not a statement of current compounding eligibility. Advisory committee recommendations are non-binding and do not, by themselves, establish authorization for human use. Read the official FDA meeting materials.
Section 8 — PYXAX Verification Standard
PYXAX uses accredited independent laboratories in its verification network, including ILS Labs, Krause Analytical, and Janoshik. The current per-batch panel covers purity by HPLC, potency against label claim, and identity by LC-MS. A lot-specific COA is published in the COA Library before dispatch and names the laboratory that tested that batch. Endotoxin, heavy-metals, and final-vial sterility screening are not part of the current panel.
Testing panel:
- Chromatographic purity by HPLC
- Molecular identity by LC-MS
- Lot-specific COA published in the PYXAX COA Library before dispatch
Lot-specific documentation. Every production lot receives its own batch number. The batch number on the vial matches the batch number on the COA in the PYXAX COA Library, so researchers can confirm identity before ordering.
Community verification. Select lots are submitted to Janoshik Analytical for community verification, with results publicly searchable by batch number — no vendor contact required. Founding batches were verified through Krause Analytical (accredited US laboratory), and ongoing production lots are tested across the accredited-laboratory network described above, with a lot-specific COA required before dispatch.
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All PYXAX compounds are supplied strictly for in-vitro and preclinical laboratory research use only. Not for human consumption. Not for veterinary use. Not for diagnostic procedures. These statements have not been evaluated by the FDA. Researchers are responsible for compliance with all applicable laws and regulations governing the use of research compounds in their jurisdiction.
Further context: Interpret peptide purity and analytical testing.