Cloning and characterization of the guinea pig neuropeptide Y receptor Y5

The Y5 receptor has been postulated to be the main receptor mediating NPY-i nduced food intake in rats, based on its pharmacological profile and mRNA d istribution. To further characterize this important receptor subtype, we is olated the Y5 gene in the guinea pig, a widely used laboratory animal in wh ich all other known NPY receptors (Y1, Y2, Y4, y6) [2,13,33,37] have recent ly been cloned by our group. Our results show that the Y5 receptor is well conserved between species; guinea pig Y5 displays 96% overall amino acid se quence identity to human Y5, the highest identity reported for any non-prim ate NPY receptor orthologue, regardless of subtype. Thirteen of the twenty substitutions occur in the large third cytoplasmic loop. The identities bet ween the guinea pig Y5 receptor and the dog, rat, and mouse Y5 receptors ar e 93%, 89%, and 89% respectively. When transiently expressed in EBNA cells, the guinea pig Y5 receptor showed a high binding affinity to iodinated por cine PYY with a dissociation constant of 0.41 nM. Competition experiments s howed that the rank order of potency for NPY-analogues was PYY = NPY = NPY2 -36 > gpPP > rPP >> NPY 22-36. Thus the pharmacological profile of the guin ea pig Y5 receptor agrees well with that reported for the Y5 receptor from other cloned species. (C) 2001 Elsevier Science Inc. All rights reserved.