Molecular Cloning, Characterization, and Localization of the Human Homolog to the Reported Bovine NPY Y3 Receptor: Lack of NPY Binding and Activation

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Abstract
A cDNA clone encoding the human homolog of the bovine cDNA clone LCR1 was isolated from a human lung cDNA library. The 1,670-bp-long nucleotide sequence predicts a single open reading frame of 352 amino acids, with a 92% amino acid identity to a bovine sequence reported to represent the neuropeptide Y (NPY) Y3 receptor. The amino acid sequence shares features common to many other G-protein-coupled receptors, including the seven transmembrane regions and putative glycosylation and phosphorylation sites. Polymerase chain reaction (PCR) analysis of human-hamster hybrid cell DNA reveals that the corresponding gene is located on human chromosome 2. Although the ligand for the bovine receptor has previously been identified as NPY in binding studies, extensive analysis with the human homolog transfected in several different cell lines failed to confirm this classification. Furthermore, the receptor shows 36% identity to both the human interleukin-8 (IL-8) and angiotensin II receptors but only 21% identity to the human NPY Y1 receptor. In addition, NPY and a number of other ligands fail to induce any change in cytosolic calcium levels in transfected cells, suggesting that this clone represents a novel neuropeptide receptor.