Comparison · 2026-09-24
Scientific lead: Alice Kay, Ph.D.
MOTS-c vs SS-31: Research Comparison
Research-use notice: This page records catalogue differences only: sequences, receptor classes, fill sizes, and Certificate of Analysis rows. It is not a protocol. It is not medical or veterinary advice, and it does not rank materials for personal use. BlueNex Labs materials are research use only. Research-use-only labelling is not a Health Canada authorization and it does not create a Drug Identification Number.
MOTS-c and SS-31 are both filed under mitochondrial language, and the shared adjective hides two different origins. One peptide is encoded by a short open reading frame in mitochondrial DNA. The other is a synthetic tetrapeptide designed in a medicinal-chemistry series and discussed at the inner membrane. Sixteen residues versus four is the first check. For the class page, see mitochondrial peptides. For the glossary class term, see mitochondrial peptide.
An open reading frame versus a designed tetrapeptide
Lee and colleagues reported a 16-amino-acid peptide encoded by a short open reading frame in the mitochondrial 12S rRNA and named it MOTS-c (Cell Metabolism, 2015, PMID 25738459). The sequence in that paper is Met-Arg-Trp-Gln-Glu-Met-Gly-Tyr-Ile-Phe-Tyr-Pro-Arg-Lys-Leu-Arg. They discussed cellular-energy models, including the folate cycle and AMPK, in the systems they measured. This page cites the paper for the sequence and for that class of model. It does not restate the paper's animal endpoints as a property of a catalogue vial. For the compound guide, see What is MOTS-c?. For the glossary line, see MOTS-c.
SS-31 is a tetrapeptide in the Szeto-Schiller series, also discussed as elamipretide. Zhao and colleagues described the cell-permeable peptide D-Arg-Dmt-Lys-Phe-NH2, where Dmt is 2,6-dimethyltyrosine, in the Journal of Biological Chemistry in 2004 (PMID 15178689). Four residues, two of them non-proteinogenic in the usual ribosomal sense (a D-arginine and a dimethyltyrosine), put this chain outside mitochondrial translation. Later papers discuss association with cardiolipin in the inner mitochondrial membrane. That membrane sentence is a target-class description. It is not a second name for MOTS-c, and it is not a lot specification. For the compound guide, see What is SS-31?. For the glossary line, see SS-31.
Same shelf, different masses
A correct mass for a 16-residue chain will not match a tetrapeptide, so a swapped PDF should fail the identity check if someone actually compares the numbers. The failure mode this page is written to prevent is filing the wrong sample name before the mass is read. Write MOTS-c or SS-31 on the line first. The mitochondrial category hub also lists NAD+, AICAR, epithalon, and other reagents. NAD+ is a cofactor. AICAR is an AMPK-pathway reagent. Epithalon is a different tetrapeptide, Ala-Glu-Asp-Gly, and it is not SS-31. Humanin is a historical mitochondrial open-reading-frame peptide in the 2015 paper and is not a shop URL.
| Record | MOTS-c | SS-31 |
|---|---|---|
| Sequence or length | 16 residues, MRWQEMGYIFYPRKLR | 4 residues, D-Arg-Dmt-Lys-Phe-NH2 |
| Molecular class | Mitochondrial open-reading-frame peptide | Synthetic Szeto-Schiller tetrapeptide |
| Receptor or target class | Discussed in mitochondrial-nuclear and cellular-energy models, including AMPK-linked readouts in the 2015 paper | Discussed at the inner mitochondrial membrane, including cardiolipin association in later papers |
| Catalogue sizes | 10 mg and 40 mg | 10 mg and 50 mg |
| COA | 10 mg: View certificate. 40 mg, purity and endotoxin: View certificate. | 10 mg: View certificate. The 50 mg listing has no library row. |
Catalogue fills
MOTS-c 10 mg and 40 mg are separate shop URLs. A 10 mg report does not document a 40 mg vial. The 40 mg library row publishes its own purity COA and endotoxin file. A report for a different fill does not document this listing. SS-31 10 mg and 50 mg are also separate shop URLs. Stock can show sold out on either or both. Sold-out status is inventory. It does not change the sequence, and it does not create a backorder. The published SS-31 10 mg report is on the SS-31 10 mg certificate. The 50 mg listing has no library row.
How to read a peptide COA still governs the MOTS-c file that does exist: sample name, area percent, and mass against the 16-residue sequence. Dimethyltyrosine and a D-residue, when the name is SS-31, have to be in the calculated mass. Comparing an SS-31 spectrum with the MOTS-c formula will fail for chemical reasons, not because the file is unreadable.
Procurement
Fulfilment is domestic: Interac e-Transfer, then Canada Post Xpresspost. For the note, see Canada laboratory procurement. Move sealed vials into controlled storage the day they arrive. The older class roundup, mitochondrial peptides as a research class, is background. Use this page when the question is which of these two sequences is in the glass. Research use only. Not for human or veterinary use.
Frequently asked questions
- Is SS-31 a shorter form of MOTS-c?
- No. MOTS-c is a 16-residue peptide encoded by a short open reading frame in mitochondrial 12S rRNA. SS-31 is a synthetic four-residue sequence discussed at the inner mitochondrial membrane. Length and origin both differ.
- Does the MOTS-c certificate cover SS-31?
- No. MOTS-c 10 mg and 40 mg each have a library anchor. A 10 mg report does not document a 40 mg vial. SS-31 10 mg has its own report on the SS-31 10 mg certificate. SS-31 50 mg has no library row. A MOTS-c file does not document either SS-31 fill.
- Are NAD+ and AICAR part of this comparison?
- No. They share the mitochondrial category route. NAD+ is a redox cofactor and AICAR is a reagent. Neither is the peptide in this table.
Research use only. BlueNex Labs does not provide medical or veterinary advice. Confirm your institution’s policies before purchase. How a comparison or class note is checked sits on documentation standards. The biochemist of record is Alice Kay, Ph.D.