Cloning and Expression of a G Protein-Linked Acetylcholine Receptor from Caenorhabditis elegans

Authors

  • Yong-Seok Lee,

    1. Molecular Neurobiology Laboratory, Institute for Molecular Biology and Genetics, Department of Biology, Seoul National University, Seoul, Korea
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  • Yang-Seo Park,

  • Deok-Jin Chang,

    1. Molecular Neurobiology Laboratory, Institute for Molecular Biology and Genetics, Department of Biology, Seoul National University, Seoul, Korea
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  • Jung Me Hwang,

  • Churl Ki Min,

    1. Department of Biological Sciences, Ajou University, Suwon, Korea
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  • Bong-Kiun Kaang,

    1. Molecular Neurobiology Laboratory, Institute for Molecular Biology and Genetics, Department of Biology, Seoul National University, Seoul, Korea
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  • Nam Jeong Cho


  • Abbreviations used : ACh, acetylcholine ; CFTR, cystic fibrosis transmembrane conductance regulator ; GIRK, G protein-gated inwardly rectifying K+ channel ; hK, high K+ ; 5-HT, 5-hydroxytryptamine ; i3 loop, third intracellular loop ; mAChR, muscarinic acetylcholine receptor ; m1-m5 and hm1-hm5, five mAChR subtypes and five human mAChR subtypes, respectively ; NMS, N-methylscopolamine.

Address correspondence and reprint requests to Dr. N. J. Cho at Department of Biochemistry, College of Natural Sciences, Chungbuk National University, Cheongju, 361-763, Korea.

Abstract

Abstract : We have isolated a cDNA clone from the nematode Caenorhabditis elegans that encodes a protein of greatest sequence similarity to muscarinic acetylcholine receptors. This gene codes for a polypeptide of 682 amino acids containing seven putative transmembrane domains. The amino acid identities, excluding a highly variable middle portion of the third intracellular loop, to the human m1-m5 receptors are 28-34%. When this cloned receptor was coexpressed with a G protein-gated inwardly rectifying K+ channel (GIRK1) in Xenopus oocyte, acetylcholine was able to elicit the GIRK current. This acetylcholine-induced current was substantially inhibited by the muscarinic antagonist atropine in a reversible manner. However, another muscarinic agonist oxotremorine and antagonists scopolamine and pirenzepine had little or negligible effects on this receptor. Taken together, these results suggest that the cloned gene encodes a G protein-linked acetylcholine receptor that is most similar to but pharmacologically distinct from muscarinic acetylcholine receptors.

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