Cloning and functional expression of a human Y4 subtype receptor for pancreatic polypeptide, neuropeptide Y, and peptide YY.
The pancreatic polypeptide family includes pancreatic polypeptide (PP), neuropeptide Y (NPY), and peptide YY (PYY). Members of the PP family regulate numerous physiological processes, including appetite, gastrointestinal transit, anxiety, and blood pressure. Of the multiple Y-type receptors proposed for PP family members, only the Y1 subtype has been cloned previously. We now report the cloning of an additional Y-type receptor, designated Y4, by homology screening of a human placental genomic library with transmembrane (TM) probes derived from the rat Y1 gene. The Y4 genomic clone encodes a predicted protein of 375 amino acids that is most homologous to Y1 receptors from human, rat, and mouse (42% overall; 55% in TM). 125I-PYY binding to transiently expressed Y4 receptors was saturable (pKd = 9.89) and displaceable by human PP family derivatives: PP (pKi = 10.25) approximately PP2-36 (pKi = 10.06) > PYY (pKi = 9.06) approximately [Leu31,Pro34]NPY (pKi = 8.95) > NPY (pKi = 8.68) > PP13-36 (pKi = 7.13) > PP31-36 (pKi = 6.46) > PP31-36 free acid (pKi < 5). Human PP decreased [cAMP] and increased intracellular [Ca2+] in Y4-transfected LMTK- cells. Y4 mRNA was detected by reverse transcriptase-polymerase chain reaction in human brain, coronary artery, and ileum, suggesting potential roles for Y4 receptors in central nervous system, cardiovascular, and gastrointestinal function.
JOURNAL OF BIOLOGICAL CHEMISTRY (1995-11-10) .
Cloning and functional expression of cDNAs encoding human and rat pancreatic polypeptide receptors.
Yan H, et al .
PCR was used to isolate nucleotide sequences that may encode novel members of the neuropeptide Y receptor family. By use of a PCR product as a hybridization probe, a full-length human cDNA was isolated that encodes a 375-aa protein with a predicted membrane topology identifying it as a member of the G-protein-coupled receptor superfamily. After stable transfection of the cDNA into human embryonic kidney 293 cells, the receptor exhibited high affinity (Kd = 2.8 nM) for 125I-labeled human pancreatic polypeptide (PP). Competition binding studies in whole cells indicated the following rank order of potency: human PP = bovine PP > or = human [Pro34]peptide YY > rat PP > human peptide YY = human neuropeptide Y. Northern blot analysis revealed that human PP receptor mRNA is most abundantly expressed in skeletal muscle and, to a lesser extent, in lung and brain tissue. A rat cDNA clone encoding a high-affinity PP receptor that is 74% identical to the human PP receptor at the amino acid level was also isolated. These receptor clones will be useful in elucidating the functional role of PP and designing selective PP receptor agonists and antagonists.