This peptide of 28 amino acids, in which the serine3 residue is n-octanoylated, is an endogenous ligand specific for growth hormone secretagogue receptor (GHS-R).
H - Gly - Ser - [Ser(n - octanoyl)] - Phe - Leu - Ser - Pro - Glu - His - Gln - Arg - Val - Gln - Gln - Arg - Lys - Glu - Ser - Lys - Lys - Pro - Pro - Ala - Lys - Leu - Gln - Pro - Arg - OH