Potent, selective peptide agonist for the neuropeptide Y Y5 receptor (IC50 values for inhibition of NPY binding to human Y5, Y1, Y2 and Y4 receptors are 0.24, 530, > 500, and 51 nM respectively, Ki at Y5 = 0.1 - 0.15 nM). Stimulates food intake in vivo.

Neuropeptide Y (22-36), a 15 amino acid peptide, is a fragment of Neuropeptide Y.Neuropeptide Y (NPY) is a 36 amino-acid neuropeptide that is involved in various physiological and homeostatic processes in both the central and peripheral nervous systems. NPY has been identified as the most abundant peptide present in the mammalian central nervous system, which consists of the brain and spinal cord. It is secreted alongside other neurotransmitters such as GABA and glutamate.

WAY-639889 is a small molecule compound with selective and potent inhibitory effects on neuropeptide Y-5 receptors.