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.