Irisin
FNDC5 fragment · Fibronectin Type III Domain-Containing Protein 5 cleavage product · Exercise hormone
An exercise-induced myokine peptide cleaved from FNDC5, released by muscle during exercise and studied for its roles in fat browning, bone density, cognitive health, and metabolic disease protection.
Half-Life
Short plasma half-life (~2-3 hours estimated); circulating levels increase rapidly with exercise and return to baseline within hours
MW
~12,587 Da (112 AA)
Amino Acids
112 AA
Evidence
Preclinical
Regulatory Status
Not approved by any regulatory authority. No irisin therapeutic approved for human use. Active pharmaceutical development for obesity and metabolic disease.
In Plain English
Sometimes called the "exercise hormone," irisin is released by your muscles when you work out and carries messages to other tissues — telling fat cells to start burning instead of storing, telling bones to get stronger, and telling the brain to grow and protect itself. It's one reason why exercise protects against Alzheimer's and why physical activity affects body composition in ways beyond just burning calories.
Overview
Irisin is a 112-amino acid peptide hormone produced by skeletal muscle during exercise via cleavage of the transmembrane protein FNDC5. Discovered in 2012 by Bruce Spiegelman's lab at Harvard, it was initially heralded as the molecular mediator of exercise benefits. Irisin promotes conversion of white adipose tissue to brown-like (beige) adipose tissue, increases thermogenesis, improves insulin sensitivity, and has demonstrated effects on bone density, Alzheimer's pathology, and cognitive function in animal models. Despite controversy over whether it circulates in humans at physiologically meaningful levels, multiple human studies have confirmed its presence and exercise-responsive regulation.
Common Formats
- Recombinant irisin (research grade)
- FNDC5/irisin protein (experimental)
Storage Notes
Recombinant protein: -80°C for long-term storage, -20°C for short-term. Avoid repeated freeze-thaw cycles. Keep cold chain intact.
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Related Compounds
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A mitochondrial-derived peptide that regulates metabolic homeostasis, glucose uptake, and has shown remarkable longevity effects in animal studies.
Humanin
A mitochondria-derived peptide encoded in the 16S rRNA region with remarkable cytoprotective, anti-apoptotic, and longevity-associated properties.
Semax
A synthetic heptapeptide based on ACTH fragment with potent nootropic, neuroprotective, and stroke-recovery properties developed in Russia.
NAP Peptide
An 8-amino acid peptide fragment derived from the ADNP (Activity-Dependent Neuroprotective Protein) gene, studied for neuroprotection, cognitive support, and potential applications in Alzheimer's disease and autism spectrum disorder.
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