Mitochondrial-Derived Peptides (MDPs)

Mitochondrial-derived peptides (MDPs) are short peptides — 16 to 38 amino acids — whose coding sequences sit inside the small mitochondrial genome rather than the nuclear one. Their existence overturns a long-held assumption that mitochondria are pure ATP factories: the same genome that codes for the electron-transport chain also codes for signalling molecules that mitochondria secrete to modulate distant tissues.

The known members

Three families have primary human research support (Zhou 2024 review, Diabetol Metab Syndr, PMID 39160573):

• Humanin — a 24-amino-acid peptide encoded within the MT-RNR2 (16S rRNA) region. First identified for anti-apoptotic activity in Alzheimer's-model neurons. Now shown to signal through the formyl-peptide receptor (FPRL1/FPR3) and, separately, through a heterotrimeric CNTFR/WSX-1/gp130 receptor. See our humanin monograph.
• MOTS-c (Mitochondrial ORF of the 12S rRNA type-c) — a 16-amino-acid peptide encoded within MT-RNR1. Its dominant systemic effect is AMPK-mediated: it activates AMPK in skeletal muscle and liver, improving insulin sensitivity and shifting metabolism toward oxidative phosphorylation. See our MOTS-c monograph. Also see the MOTS-c and Exercise Restore Cardiac Function paper for cardiovascular relevance.
• SHLPs 1-6 (Small Humanin-Like Peptides) — six additional short peptides encoded near humanin in the MT-RNR2 region, sharing partial receptor engagement with humanin but with distinct tissue-specific effects. Human evidence base is thinner than for humanin and MOTS-c.

Why MDPs matter as a research target

MDPs bridge a category gap in physiology: they are the first known endocrine signals that originate from an organelle rather than a tissue. This makes them a distinctive research target because:

• They give mitochondria a direct communication channel to nuclear-encoded metabolism.
• Their circulating levels decline with age in humans (Woodhead 2021, PMID 34520826), positioning them as candidate mediators of the metabolic phenotype of ageing.
• Exercise elevates them acutely and chronically — MDPs may be part of the molecular explanation for exercise's systemic effects beyond skeletal muscle.

Not the same as mitochondria-targeted peptides

MDPs (endogenous, mitochondrially encoded, secreted) are frequently confused with mitochondria-targeted synthetic peptides — the SS-31 / elamipretide class — which are nuclear-encoded synthetic drugs designed to accumulate at the inner mitochondrial membrane and stabilise cardiolipin. Different molecular class, different origin, different mechanism. See our SS-31 monograph for that pharmacological approach and the SS-31 vs MOTS-c comparison for the direct contrast.

Regulatory status

None of the MDPs or the mitochondria-targeted synthetics is a licensed medicine in the UK. All are investigational research compounds. Their evidence bases are early — a mixture of mechanism-of-action studies, animal models, and small human PK / biomarker studies. Public claims about MDPs as anti-ageing or metabolic-improvement products should be treated as ahead of the evidence.