Signal, carrier and neurotransmitter peptides: what’s the difference?

Three mechanisms get sold under one word. Knowing which one you’re buying tells you what to expect, how long it takes, and what it was never going to do.

Signal peptides

Signal peptides are fragments of larger proteins that fibroblasts — the cells responsible for building collagen — recognise as an instruction to increase production. Matrixyl 3000 is the best-known example. The effect is structural and cumulative: you are asking skin to build more of something over weeks, not triggering an immediate change.

Because the mechanism is upstream of visible change — more collagen synthesis, which then has to actually remodel skin — results at this category typically take six to twelve weeks to become apparent, and stopping use does not undo existing gains as quickly as it took to build them.

Carrier peptides

Carrier peptides are built around binding and delivering a trace element — almost always copper — into skin, where that element participates in enzymatic processes involved in collagen and elastin synthesis and general repair signalling. Copper peptides (GHK-Cu) are the category’s only well-evidenced example in cosmetic use.

The mechanism is subtly different from a pure signal peptide — it is delivering an ingredient to a process rather than directly instructing a cell — but the practical outcome and timeline are similar: gradual, structural, and best judged over three months. Full detail on the pillar page.

Neurotransmitter-inhibitor peptides

This category works on an entirely different target: not collagen, but the signalling that causes facial muscles to contract. Argireline (acetyl hexapeptide-8) is the standard example, modestly interfering with the release mechanism involved in muscle contraction at the skin’s surface — at a small fraction of the effect of an injectable, but through a related concept.

Enzyme-inhibitor peptides

A smaller, less commercially prominent category: peptides that slow the enzymes responsible for breaking existing collagen down, rather than stimulating new production. Several are derived from plant proteins, most commonly soy. The evidence base for specific examples in this category is generally thinner than for the three above, and we have not yet found one strong enough to carry its own grade-A page — when we do, it will appear in the Library.

Can you combine categories?

Generally yes, and it is often sensible — a signal or carrier peptide for structural collagen support alongside a neurotransmitter-inhibitor for expression lines addresses two different problems at once. The one genuine layering caveat in this group is copper peptide’s sensitivity to pure vitamin C and low pH, covered on how to use copper peptides. Matrixyl and Argireline do not carry that same restriction.