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How Peptides Work
Every peptide has a target — usually a receptor on the surface of a cell. The peptide is shaped like a key, the receptor is the lock, and the cell only responds when the right key fits.
Step 1 — Binding
The peptide travels through blood or tissue fluid until it finds its receptor. Receptors are picky; BPC-157 doesn't trigger insulin release, and insulin doesn't trigger angiogenesis.
Step 2 — Signal cascade
Binding flips a switch inside the cell. The most common pathways are GPCRs (G-protein coupled receptors) and tyrosine kinases. Either way, second messengers like cAMP or calcium amplify the signal.
Step 3 — Cellular response
The cell changes behavior — opens an ion channel, transcribes new mRNA, releases another hormone, divides, or dies. The downstream effect is what researchers actually measure.
Why this matters for research
Specificity is everything. Ipamorelin only hits GHS-R. Semaglutide only hits the GLP-1 receptor. That precision is why peptides often have cleaner side-effect profiles than small-molecule drugs.