Abstract: The present invention provides novel NPY/PYY receptor proteins and the nucleic acid sequence encoding them. The invention is directed to the isolation, characterization, and pharmacological use of these receptors and nucleic acids. In particular, this invention provides human and rat NPY/PYY receptors (which we call the NPY Y5 receptor) and nucleic acids. Also provided are recombinant expression constructs useful for transfecting cells and expressing the protein in vitro and in vivo. The invention further provides methods for detecting expression levels of the protein as well as methods for screening for receptor antagonists and agonists to be used for the treatment of obesity or anorexia, respectively.