Screening analogs of the cyclic lactam melanocortin agonist MTII led to the identification of the agoutimimetic SHU9119. The cyclopeptide SHU9119 shares pharmacological properties with the agouti peptide in that it is a potent antagonist of the melanocortin-4 receptor and a less potent antagonist of the melanocortin-3 receptor.ONE-LETTER SEQUENCE: Ac-Nle-cyclo(-DH-D-2-Nal-RWK-NH2)MOLECULAR FORMULA: C54H71N15O9MOLECULAR WEIGHT:1074.25STORAGE CONDITIONS: -20 5C, CAS REGISTRY NUMBER: [168482-23-3], SYNONYMS: melanotropinsRESEARCH AREA: HormonalREFERENCES: V.J.Hruby et al., J. Med. Chem., 38, 3454 (1995); W.Fan et al., Nature, 385, 165 (1997)