Peptides are tiny protein fragments that cells use as messengers to send...

https://yourhealthmagazine.net/article/health-news-research/how-peptides-help-scientists-understand-cell-communication/

Peptides are tiny protein fragments that cells use as messengers to send signals by binding to specific receptors. Researchers study these interactions to understand how receptors work, how selective they are, and which signaling pathways they trigger