NCIt definition : Met-enkephalin (5 aa, 1 kDa) is encoded by the human PENK and POMC genes. This protein
plays a role in the activation of delta opioid receptors.;
NCIt note : Proenkephalin-A has multiple sequences that can be cleaved to release Met-enkephalin,
while pro-opiomelanocortin contains one Met-enkephalin peptide. (UniProt);