Abstract

The polymerase chain reaction was used to isolate novel GTP-binding protein (G protein)-coupled receptors from bovine locus coeruleus (LC), a brain region enriched in the neuropeptide Y (NPY) system, using degenerate primers derived from the third and sixth transmembrane domains of known G protein-coupled receptors. Partial sequence analysis revealed that the polymerase chain reaction cDNA fragments were homologous to other G protein-coupled receptors. One of these cDNA fragments was used to isolate a full length cDNA clone, referred to as LCR1, from an LC cDNA library. LCR1 is 1.7 kilobases in length and encodes a predicted protein of 353 amino acids, with a membrane topology similar to that of other G protein-coupled receptors. Expression of LCR1 in mammalian cells revealed saturable and specific high affinity binding for 125I-NPY but not for any of the other ligands tested. Northern blot analysis revealed that labeled LCR1 DNA hybridized with a predominate mRNA transcript of approximately 1.7 kilobases, which was found to be most abundant in LC, cerebellum, and pons, intermediate in dorsal raphe, substantia nigra, and thalamus, and lowest in cerebral cortex and neostriatum. Significant levels of LCR1 mRNA were also present in heart, kidney, lung, and liver. This cDNA clone will be useful for studies of the regulation and function of NPY receptors, as well as for the isolation of related NPY receptor subtypes.