A synthetic four-amino-acid peptide engineered — not naturally occurring — to enter mitochondria and act on the inner mitochondrial membrane. Where MOTS-c is a signal, SS-31 is a purpose-built repair tool.
SS-31, also called elamipretide, is a very short, engineered peptide designed to reach the inner mitochondrial membrane. Unlike MOTS-c, it isn't a hormone your body already makes — it's a purpose-built research tool.
SS-31 binds cardiolipin, a fat found almost exclusively in the inner mitochondrial membrane that helps hold the energy-production machinery in shape. When mitochondria are stressed or aged, the inner folds (cristae) become disorganised, electrons leak instead of moving cleanly, more reactive oxygen species form, and ATP production gets less efficient.
SS-31 is studied for stabilising that membrane environment: improving electron-transport organisation, reducing electron leak and excess reactive oxygen species, and improving how efficiently respiration is coupled to ATP production. Some research also points to interactions with proteins involved in ADP/ATP transport.
SS-31 has more human clinical development than MOTS-c — particularly around Barth syndrome, heart function, and muscle energetics — but that's specific disease-and-aging-mitochondria research, not proof of a general anti-aging or performance benefit in healthy people.
Educational and editorial content only. Not medical advice. SS-31 is discussed here as a research/investigational compound; content may describe emerging research not approved for clinical use.