Peptides are tiny protein pieces that act like messengers, sending signals...

https://www.lima-bookmarkings.win/peptides-are-tiny-messengers-cells-use-to-send-signals-by-binding-to-specific-1

Peptides are tiny protein pieces that act like messengers, sending signals between cells by binding to specific receptors. Researchers use peptides to explore how receptors work, test how selective they are, and map out signaling pathways inside cells