A human gene encodes a putative G protein-coupled receptor highly expressed in the central nervous system

• Published in: Brain research. Molecular brain research. 1998-02, Vol.54 (1), p.152-160
• Main Authors: Donohue, Patrick J, Shapira, Hagit, Mantey, Samuel A, Hampton, Lori L, Jensen, Robert T, Battey, James F
• Format: Article
• Language: English
• Subjects: 3T3 Cells; Amino Acid Sequence; Animals; Base Sequence; Biochemistry and metabolism; Biological and medical sciences; Brain - metabolism; Central nervous system; Chromosome Mapping; Chromosomes, Human, Pair 7; Cloning, Molecular; Corpus callosum; Fetus; Fundamental and applied biological sciences. Psychology; G protein-coupled receptor; Gene Expression - genetics; GTP-Binding Proteins - metabolism; Humans; Inositol Phosphates - biosynthesis; Mice; Mice, Inbred BALB C; Molecular Sequence Data; Oocytes - metabolism; Organ Specificity - genetics; Orphan receptor; Polymerase Chain Reaction; Receptors, Cell Surface - biosynthesis; Receptors, Cell Surface - genetics; Sequence Homology, Amino Acid; Spinal Cord - metabolism; Substantia nigra; Transfection; Vertebrates: nervous system and sense organs; Xenopus
• ISSN: 0169-328X; 1872-6941
• DOI: 10.1016/S0169-328X(97)00336-7

The mammalian bombesin (Bn)-like neuropeptide receptors gastrin-releasing peptide receptor (GRP-R) and neuromedin B receptor (NMB-R) transduce a variety of physiological signals that regulate secretion, growth, muscle contraction, chemotaxis and neuromodulation. We have used reverse transcription-polymerase chain reaction (PCR) to isolate a cDNA from human brain mRNA, GPCR/CNS, that encodes a putative G protein-coupled receptor (GPCR) based upon the presence of the paradigmatic seven heptahelical transmembrane domains in its predicted amino acid sequence. Analysis of the deduced protein sequence of GPCR/CNS reveals this putative receptor to be 98% identical to the deduced amino acid sequence of a recently reported gene product and minimally identical (∼23%) to both murine GRP-R and human endothelin-B (ET-B) receptor. Our deduced protein sequence differs at 12 positions, scattered throughout the open reading frame, relative to the original sequence. A 3.7 kb GPCR/CNS mRNA species is expressed in vivo in a tissue-specific manner, with highest levels detected in brain and spinal cord, lower levels found in testis, placenta and liver, but no detectable expression observed in any other tissue. Analysis of GPCR/CNS genomic clones reveals that the human gene contains one intron that is about 21 kb in length that divides the coding region into two exons and maps to human chromosome 7q31. No specific binding is observed with either a newly identified ligand (DTyr 6, βAla 11,Phe 13,Nle 14]Bn-(6–14)) having high affinity for all Bn receptor subtypes or Bn after GPCR/CNS is stably expressed in fibroblasts. No elevation in inositol trisphosphate is observed after the application of micromolar levels of either DPhe 6, βAla 11,Phe 13,Nle 14]Bn-(6–14) or Bn, a concentration of agonist known to activate all four known Bn receptor subtypes. When GPCR/CNS is expressed in Xenopus oocytes, no activation of the calcium-dependent chloride channel is detected despite the addition of micromolar levels of Bn peptide agonists. We conclude that the natural ligand for this receptor is none of the known naturally occurring Bn-like peptides and the true agonist for GPCR/CNS remains to be elucidated.