What is a protein?
Proteins are the molecular machines and building blocks of your body: they build muscle and skin, carry oxygen, fight infections and run almost every chemical job in your cells.
If your DNA is a cookbook, proteins are the dishes cooked from its recipes, and many of those dishes turn out to be kitchen tools themselves: knives, mixers and ovens that keep the whole kitchen running.
Why it matters for aging
Each protein is a long chain of smaller building blocks called amino acids, folded into a precise 3D shape. The shape decides the job, the same way a key's shape decides which lock it opens. Your genes hold the instructions for building each one.
With age, cells get worse at keeping proteins correctly folded and clearing out damaged ones, a hallmark of aging called loss of proteostasis. Misfolded proteins can clump together, which is involved in diseases like Alzheimer's. That's one reason the cell's recycling system, autophagy, matters so much.
A common myth
Protein is just something you eat to build muscle.
Dietary protein is one source, but your body builds tens of thousands of different proteins of its own. Enzymes, many hormones, antibodies and the switches that control aging, like mTOR and AMPK, are all proteins.
Go deeper
Deep dives
- mTOR and aging: the growth switch you want on, and off
- How long do you have to fast for autophagy? The honest answer
Related terms
Updated Nov 9, 2026 · All terms