Neuropeptide Y (NPY) plays important roles in the central control of appetite and energy balance, but the receptor subtype responsible for this function has not been cloned. Here we report the cloning by expression of a novel NPY receptor subtype from a rat hypothalamus cDNA library. The novel receptor, referred to as the NPY Y5 receptor, has a transcript of approximately 2.6 kilobases with an open reading frame of 1335 base pairs that encodes a 445-amino acid protein. The amino acid sequence deduced from the rat Y5 cDNA clone shows only 30 -33% identity to other NPY receptors, including Y1, Y2, and Y4/PP1. Using the rat Y5 receptor cDNA probe, the human homologue was obtained by low stringency hybridization. The human Y5 amino acid sequence has 88% identity to the rat Y5 receptor. Importantly, pharmacological analysis shows that the rat and human Y5 receptors have high affinity for the peptides that elicit feeding (e.g. NPY, PYY, (2-36)NPY, and (LP)NPY) and low affinity for nonstimulating peptides (e.g. (13-36)NPY and rat PP), suggesting that it is the NPY feeding receptor subtype.Neuropeptide Y (NPY), 1 peptide YY (PYY), and pancreatic polypeptide (PP) are all members of a common family of hormonally active peptides. NPY is predominantly expressed in the central nervous system and is one of the most abundant neuropeptides in the brain (1). NPY has a broad range of functions, including the regulation of vascular tone, anxiogenesis, and food intake (2). These diverse physiological actions are mediated through distinct NPY receptor subtypes (3-10), three of which, Y1, Y2, and Y4/PP1, have been cloned. Another NPY receptor subtype, Y3, which is characterized by its lower affinity for PYY as compared with NPY has been reported (2). However, the feeding response elicited by NPY and its peptide analogues cannot be fully accounted for by the pharmacological profile of these receptors. Thus, although both (LP)NPY and (2-36)NPY are potent stimulators of feeding (11-14), (LP)NPY has higher affinity for the Y1 than the Y2 receptor, whereas (2-36)NPY exhibits higher affinity for the Y2 than the Y1 subtype, suggesting that neither of these receptor subtypes is exclusively involved in the feeding response (15)(16)(17)(18)(19). Likewise, Y3 receptor pharmacology indicates that it has low affinity for PYY, a potent stimulator of feeding in vivo (2). Rat PP and C-terminal fragments of NPY, on the other hand, fail to elicit feeding when injected intracerebroventricularly into mice and rats (11)(12)(13)20). Because the Y2 receptor has high affinity for such C-terminal peptide fragments (2) and PP binds strongly to the Y4/PP1 receptor (5-7), it is unlikely that these subtypes are mediators of feeding behavior. In this report, we describe the molecular identification of a novel NPY receptor subtype, referred to as the Y5 receptor. The pharmacological profile of this receptor suggests that it is the NPY feeding receptor. EXPERIMENTAL PROCEDURESIsolation of Rat Hypothalamus mRNA and Construction of cDNA Library-Total RNA was obtained ...

NPY, which is similar to that of the mouse Y4/PP1 receptor. Mouse PP2 transcripts were not detectable by Northern analysis in adult tissues and in 11-, 15-, and 17-day-old embryos. However, a 9.8-kb PP2 transcript was detectable in 7-day-old mouse embryo, i.e. prior to the organogenesis of pancreas and the onset of PP production. We have also cloned the human homologue of PP2, which is a single copy gene and maps to human chromosome 5q31. Surprisingly, the human PP2 cDNAs and gene sequences display a single base deletion in the coding region. This frameshifting mutation predicts a truncated receptor of 290 amino acids without TM7. Transfection of COS-7 cells with several different human PP2 expression constructs failed to confirm any specific binding of 125 I-PP, 125 I-PYY, or 125 I-NPY to cell membranes. These data suggest that in mouse there are at least two PP receptors, Y4/PP1 and PP2, whereas in humans, PP2 is either functionally inactive or it has acquired a PP-independent function.

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