“Endocannabinoid peptides, or “pepcans,” are endogenous ligands of the CB1 cannabinoid receptor. Depending on their length, they display diverse activity: For instance, the nona-peptide Pepcan-9, also known as hemopressin, is a powerful inhibitor of CB1, whereas the longer variant Pepcan-12, which extends by only three amino acid residues at the N-terminus, acts on both CB1 and CB2 as an allosteric modulator. These findings open the way to structure-driven design of selective peptide modulators of CB1.”

https://www.ncbi.nlm.nih.gov/pubmed/30505835

https://www.frontiersin.org/articles/10.3389/fmolb.2018.00100/full