Mitochondrial peptides: MOTS-c, humanin and SS-31
For a long time it was assumed every protein is directed from the cell nucleus. That turned out to be wrong: mitochondria have their own DNA and use it to send their own messages into the cell.
A second set of instructions in the cell
Mitochondria are the parts of the cell that supply energy. They have their own small piece of DNA, a leftover from the days when they were free-living bacteria. That DNA was long regarded as a parts list for energy production and nothing more.
Since 2003 it has been clear that it also encodes peptides which the mitochondria send outward. The power plants talk back to the rest of the cell, and even to other tissues. That is why this group has drawn so much attention in a short time.
MOTS-c
MOTS-c was one of the first to be found. In the literature it appears around energy balance, insulin sensitivity and endurance. The mechanism named most often is AMPK, the switch a cell flips when energy runs low.
What makes it special is that the signal travels from inside out. The mitochondria report that energy is getting tight, and the rest of the cell adjusts its behaviour.
Humanin
Humanin was discovered in brain tissue and owes its name to the research in which it was found. It blocks the route a cell follows when it decides to clear itself away. In work on nerve cells and ageing it therefore turns up often.
SS-31
SS-31, also known as elamipretide, belongs to this group but does not come from it: it was designed in the lab. What sets it apart is how it finds its target. It binds to cardiolipin, a fatty substance found only in the inner membrane of mitochondria.
As a result it accumulates exactly where energy production happens, with no transport mechanism needed. That is an elegant answer to a problem many substances founder on: being active, but never reaching the right place.
The first publication on these peptides dates from 2003. That is recent, certainly next to a hormone like oxytocin which has been studied for a century. Much of what is known comes from cell culture and animal work and has not been independently confirmed.
What they have in common
All three turn on the same theme: the cell has an energy crisis and must decide what to do. Survive, economise, or clear itself away. That is a different kind of question from the one the other groups raise, and it is exactly why ageing research so often treats them together.
This site is made by the team behind Apex Bio Research, a Dutch supplier of research peptides with a certificate of analysis per batch.
Visit the shopThis site explains what the scientific literature says about peptides. It is not medical advice and not a set of instructions. The substances discussed here are research compounds: they are not approved for use in humans or animals. If you have a health question, see a doctor.
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