Peptide tyrosine tyrosine (PYY) was originally isolated from porcine gut, which exhibits striking sequence homology with members of the pancreatic polypeptide family, including neuropeptide tyrosine (NPY). The peptide is localized to enteroglucagon containing (L/EG) and pancreatic (A) cells in many mammalian and non-mammalian species. PYY gene expression is upregulated by various growth factors, including growth hormone and insulin-like growth factor and the physiological effects of PYY