Mitochondrial peptides: MOTS-c, humanin and the SHLP family
Prepared by: Research Desk. Sources are linked for verification.
"Mitochondrial peptides" is a phrase that turns up more and more in science news and on social media. It sounds technical, but the core idea is simple. This explainer introduces the whole family at once: what the term means, who the main members are, how researchers study them, and how much is still unknown. If MOTS-c alone is the main interest, our beginner's guide to MOTS-c covers it in more depth.
What does "mitochondrial peptides" mean?
Mitochondria are small structures inside cells that turn food and oxygen into usable energy. Unusually, they carry their own small loop of DNA, separate from the main DNA in the cell nucleus.
For decades, scientists thought mitochondrial DNA held instructions for only a short list of energy-making parts. Researchers later found very short stretches of code, called small open reading frames, tucked inside mitochondrial genes. Some of these stretches can be read to make short chains of amino acids: peptides. Scientists call these mitochondrial-derived peptides, often shortened to MDPs [1][2].
Two features make this group interesting to researchers:
They are made from mitochondrial instructions. That's unusual, because most proteins in a cell come from the nuclear genome.
Some appear to act as signals. Reviews describe MDPs as possible messengers that link what's happening inside mitochondria to the rest of the cell and, in some studies, to other tissues [1][2][3].
Meet the family
Most reviews group the best-known MDPs into three sets: humanin, the small humanin-like peptides (SHLPs) and MOTS-c [1][2][3]. Here's a quick overview.
Peptide | Where its code sits in mitochondrial DNA | Main type of evidence so far |
|---|---|---|
Humanin | 16S rRNA gene region | Cell and animal studies; human blood measurements [4][1] |
SHLP1 to SHLP6 | 16S rRNA gene region | Mostly cell and animal studies [5][1] |
MOTS-c | 12S rRNA gene | Cell and animal studies; human exercise samples; one registered human trial [6][9][17] |
Humanin
Humanin is generally described as the first member of the family to be identified, and it has been studied for longer than the others [1][4]. A 2020 review called it "a mitochondria-derived peptide with emerging properties" and summarised laboratory and animal research across several organ systems, including the heart and blood vessels [4]. Researchers have also measured humanin levels in human blood, which is part of why it is discussed as a possible marker [14].
The SHLP family
The small humanin-like peptides are coded in the same region of mitochondrial DNA as humanin, which is how they got their name [1]. They are much less studied. One example is a 2023 animal study on SHLP2. It reported that SHLP2 acted on nerve cells in the hypothalamus, a brain area involved in appetite and energy balance, and that this was linked to changes in how the animals regulated energy [5]. That's a single line of animal research, so it tells us about a possible mechanism, not about effects in people.
MOTS-c
MOTS-c is a 16-amino-acid peptide coded in the 12S rRNA gene of mitochondrial DNA [6]. The first major description, published in 2015, reported that in mice MOTS-c influenced metabolic regulation, including measures of obesity and insulin resistance [6]. Since then, research has broadened:
A move into the nucleus (cell and mouse study, 2018). Researchers reported that under metabolic stress, MOTS-c moved from the cytoplasm into the cell nucleus and was associated with changes in nuclear gene expression [7]. A 2019 article described MOTS-c as "a mitochondrial-encoded regulator of the nucleus" [8].
Exercise and ageing (mouse experiments plus human samples, 2021). A study reported that MOTS-c levels rose in response to exercise in humans, and examined its role in age-related physical decline and muscle in mice [9].
Immune signalling (2026). A newer study described MOTS-c as an interferon-linked host defence peptide, opening a different research direction [10].
The heart (2025). In a study of the type 2 diabetic heart, the authors reported that MOTS-c restored mitochondrial respiration in heart tissue [11]. This is a single laboratory study, and it does not describe effects in people.
Several reviews summarise MOTS-c research, including one focused on its potential for future drug development and one on diabetes and ageing-related diseases [12][15]. Reviews organise existing findings; they do not add new data.
Why researchers study them as a group
Scientists increasingly see these peptides as part of a broader idea: that stressed or active mitochondria release signals, sometimes called mitokines, which may affect other parts of the body. A 2023 review on mitochondrial stress and mitokines in ageing placed MDPs within this wider picture [13].
Three research themes come up again and again:
Ageing. Reviews discuss whether MDP levels change with age and how this might relate to healthspan [1][13].
Metabolism. Many studies look at insulin, glucose and energy balance. Reviews on diabetes and on energy metabolism summarise this work, mostly from animal models [2][3][15].
Biomarkers. Some researchers are asking whether blood levels of MDPs could serve as markers of cardiometabolic problems, a question that is still being tested [14].
An evolutionary angle also appears in the literature. A 2024 review discussed evolutionary perspectives on these peptides alongside their metabolic research [3].
Exercise: the most-studied human connection
The clearest human data on MDPs involve exercise. Here, researchers measure natural levels in blood or muscle before and after physical activity. They aren't giving anyone a peptide. A 2026 systematic review pulled together studies on MDPs that respond to physical exercise and discussed them as possible research targets in metabolic disorders [16]. The 2021 MOTS-c study also reported exercise-related changes in human samples [9].
This is an important distinction. "Levels went up after exercise" describes what the body produced on its own. It is not evidence about a manufactured version of the peptide.
What about human trials and legal status?
For MOTS-c, a registered study (NCT07505745) is listed on ClinicalTrials.gov. Its record concerns MOTS-c and insulin sensitivity in adults with prediabetes and overweight or obesity [17]. Details such as study design, timelines and recruitment status are set out on the registry itself and can change over time, so the record is the place to confirm them.
On the regulatory side, the FDA publishes meeting pages for its Pharmacy Compounding Advisory Committee, including one for the meeting held on 23–24 July 2026 [18]. Separately, the World Anti-Doping Agency publishes its Prohibited List, the reference document for substances banned in tested sport [19]; the current edition of that list is where the status of any substance is set out. None of the sources cited on this page is an FDA approval record for MOTS-c, humanin or any SHLP; they describe research studies, a trial registration and regulatory processes. Our page on MOTS-c's legal and FDA status walks through the regulatory picture in plain English.
How to read headlines about mitochondrial peptides
Because this field is young, headlines often run ahead of the evidence. A few quick checks are useful:
Which species? A mouse result is a starting point, not an answer about people.
Measured or given? Natural levels measured after exercise are a different question from effects of a manufactured peptide.
Primary study or review? Reviews summarise others' work. They don't add new data.
Which peptide? Humanin, SHLP2 and MOTS-c are different molecules. A finding for one doesn't carry over to the others.
We explain how we choose and label sources on our About page.
Frequently asked questions
Are mitochondrial peptides the same as mitochondrial proteins?
Not quite. Most proteins found in mitochondria are coded by nuclear DNA and then imported. Mitochondrial-derived peptides are short chains coded within mitochondrial DNA itself, often in small stretches hidden inside larger genes [1][2].
Is humanin the same thing as MOTS-c?
No. Both are mitochondrial-derived peptides, but they come from different genes: humanin from the 16S rRNA region and MOTS-c from the 12S rRNA gene [1][6]. They have different sequences and are studied as separate molecules.
Is any mitochondrial peptide an approved medicine?
None of the sources on this page is an FDA approval record for any of the peptides covered here. For MOTS-c, the human research cited is a registered trial on insulin sensitivity in adults with prediabetes and overweight or obesity [17]. The rest of the evidence comes mostly from cell and animal studies.
Further reading
Books are still one of the most efficient ways to build a solid base in cell biology before tackling primary research. A good introductory text explains organelles, DNA, energy production and cell signalling in a logical order, so later articles make far more sense.
When comparing options, look at the publication date (cell biology moves quickly), whether the author has a research or teaching background in the field, whether claims come with references, and whether the level suits a newcomer or a student. Format matters too: illustrated print editions often make diagrams easier to follow, while e-books and audiobooks win on price and portability.
Price transparency is worth checking as well. Second-hand copies of earlier editions can be a sensible, low-cost choice for the basics, while newer editions are the better pick for recent discoveries. Reader reviews that mention clarity and accuracy tend to be more useful than star ratings alone.
A shortlist of two or three titles at different depths, such as one general-audience overview and one textbook-style reference, usually covers most needs without overspending.
Last updated: 19 October 2026.
Related on this site
Is MOTS-c legal? FDA status and anti-doping rules, simply explained
Best books on mitochondria for beginners: a 2026 reading list
How to evaluate MOTS-c claims online: a beginner's checklist
Exercise and MOTS-c: what the research shows, in plain English
Not medical advice. This page reports published research and regulatory records for information only.
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