Neuropeptide Y (NPY), peptide YY (PYY), and pancreatic polypeptide (PP) are structurally related peptides found in all higher vertebrates. NPY is expressed exclusively in neurons, whereas PYY and PP are produced primarily in gut endocrine cells. Several receptor subtypes have been identified pharmacologically, but only the NPY/PYY receptor of subtype Y1 has been cloned. This is a heptahelix receptor that couples to G proteins. We utilized Y1 sequence information from several species to clone a novel human receptor with 43% amino acid sequence identity to human Y1 and 53% identity in the transmembrane regions. The novel receptor displays a pharmacological profile that distinguishes it from all previously described NPY family receptors. It binds PP with an affinity (Ki) of 13.8 pM, PYY with 1.44 nM, and NPY with 9.9 nM. Because these data may identify the receptor as primarily a PP receptor, we have named it PP1. In stably transfected Chinese hamster ovary cells the PP1 receptor inhibits forskolin-stimulated cAMP synthesis. Northern hybridization detected mRNA in colon, small intestine, pancreas, and prostate. As all three peptides are present in the gut through either endocrine release or innervation, all three peptides may be physiological ligands to the novel NPY family receptor PP1.

In contrast, cyclo S±S [Cys20,Cys24]pNPY was found to be a highly selective ligand at the Y 2 -receptor, binding only threefold less efficiently than NPY. Analogues containing variations of positions 31 and 32 showed highly reduced affinity to the Y 1 -receptor, while binding to the Y 5 -receptor was affected less. Inhibition of cAMP-accumulation of selected peptides with replacements within position 20±23 of NPY showed preserved agonistic properties. The NPY analogues tested give insights into ligand±receptor interaction of NPY at the Y 1 -, Y 2 -and Y 5 -receptor and contribute to our understanding of subtype selectivity. Furthermore, the Y 1 -receptor-preferring peptides are novel tools that will provide insight into the physiological role of the Y 1 -receptor.Keywords: food intake; neuropeptides; NPY; selective ligands; structure±affinity relationship.Obesity, food intake and energy homeostasis are key areas of growing importance because obesity is beginning to replace malnutrition and infectious diseases as the most significant contributor to ill health in the developed world [1]. Neuropeptide Y (NPY) is one of the most important effector molecules of leptin: it is a key molecule in the regulation of food intake, it acts via several different receptor subtypes and elicits several physiological effects. Profound effects on stimulation of food intake, secretion of luteinizing and growth hormone, and insulin release suggest an important role for NPY in the pathophysiology of obesity and diabetes [2±5]. A wide range of other effects of NPY have been reported, such as potent vasoconstriction [6], facilitation of learning and memory [7], modulation of locomotor behaviours [8], induction of hypothermia [9,10], inhibition of sexual behaviour [11], shifts in circadian rhythms [12], modulation of cardiorespiratory parameters[13], anxiolytic potency [14] and inhibition of alcohol consumption and resistance [15].NPY is a 36-amino acid peptide amide belonging to the family of pancreatic polypeptides that includes also pancreatic polypeptide (PP) and peptide YY; it was first isolated from pig brain in 1982 [16].NPY is widely distributed within the central nervous system and in the periphery. [25,26]. A putative Y 3 -receptor has been described only pharmacologically and no specific agonists or antagonists are known [27]. All receptors belong to the G-protein coupled receptor superfamily [28]. The correlation of a certain receptor subtype to a distinct physiological effect is not yet fully understood. Recent studies even suggest that different receptor subtypes redundantly mediate identical actions in a given system, as has been shown for the Y 1 -and Y 5 -receptor in the regulation of food intake [3]. Findings that deficiencies in either the Y 1 -or the Y 5 -receptors do not significantly impair the normal feeding response to fasting or NPY stimulation, strongly indicate that both Y receptors are involved in appetite regulation by NPY [29,30]. Selective receptor agonists or antagonists are useful tools with which to stu...

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Neuropeptide Y (NPY) is an abundant and widespread neuropeptide in the nervous system of mammals. NPY belongs to a family of 36-amino acid peptides that also includes pancreatic polypeptide and the endocrine gut peptide YY as well as the fish pancreatic peptide Y. To study the evolution of this peptide family, we have isolated clones encoding NPY from central nervous system cDNA libraries of chicken, goldfish, and the ray Torpedo marmorata, as well as from a chicken genomic library. The predicted chicken NPY amino acid sequence differs from that of rat at only one position. The goldfish sequence differs at five positions and shows that bony fishes have a true NPY peptide in addition to their pancreatic peptide Y. The Torpedo sequence differs from that of rat at three positions. As Torpedo NPY has no unique positions when compared with the other sequences, it seems to be identical to the NPY of the common ancestor ofcartilaginous fishes, bony fishes, and tetrapods after 420 million years of evolution. The 30-amino acid carboxyl-terminal extension of the NPY precursor also displays considerable sequence conservation. These results show that NPY is one ofthe most highly conserved neuroendocrine peptides.Neuropeptide Y (NPY) was first purified from porcine brain (1). The name is derived from its amino-and carboxylterminal tyrosines (single-letter code Y). Subsequently, NPY sequences have been determined for six other mammals (2) and for a frog (3), revealing a remarkable degree of conservation. NPY occurs abundantly in the mammalian central nervous system as well as in the peripheral nervous system (4) and has been shown to have both pre-and postsynaptic actions (5).NPY belongs to a family of peptides that includes the gut endocrine peptide YY (PYY) and the pancreatic endocrine peptides called pancreatic polypeptide (PP) in tetrapods and peptide tyrosine (PY) in fish. All of these peptides consist of 36 amino acids and have a carboxyl-terminal amide. Porcine NPY and PYY show 70% sequence identity and can act on the same receptors with similar potencies (6), whereas porcine PP is only 50% identical to NPY and PYY and appears to have distinct receptors (7-9). PP differs considerably between species; PP of pig, chicken, and bullfrog share only 44-58% identity.Pancreatic peptides have been isolated and sequenced from four different species of fish (2). Surprisingly, these peptides were found to be more similar to mammalian NPY and PYY than to PP. Because of the unclear relationships with the mammalian peptides, the fish pancreatic peptides have been given different names by different groups of investigators. We use here the designation PY.Immunohistochemical studies of NPY, PYY, and PP have been interpreted to indicate that PP appeared first in evolution (10), and sequence and receptor-binding analyses have suggested that PP forms one evolutionary lineage whereas NPY and PYY form a separate lineage and diverged from each other more recently (11). To extend the structural evolutionary analyses, we decided to isol...

Guinea-pig neuropeptide Y 1 and rat pancreatic polypeptide Y 4 receptors expressed in Chinese hamster ovary cells were internalized rapidly upon attachment of selective peptide agonists. The Y 1 and Y 2 , but not the Y 4 , receptor also internalized the nonselective neuropeptide Y receptor agonist, human/rat neuropeptide Y. The internalization of guinea-pig neuropeptide Y 2 receptor expressed in Chinese hamster ovary cells was small at 37 8C, and essentially absent at or below 15 8C, possibly in connection to the large molecular size of the receptor2ligand complexes (up to 400 kDa for the internalized fraction). The rate of intake was strongly temperature dependent, with essentially no internalization at 6 8C for any receptor.