Cloning and functional expression of a Drosophila gamma-aminobutyric acid receptor

• Published in: Proceedings of the National Academy of Sciences - PNAS 1994-06, Vol.91 (13), p.6069-6073
• Main Authors: Chen, R, Belelli, D, Lambert, J.J, Peters, J.A, Reyes, A, Lan, N.C
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; amino acid sequences; Animals; antagonists; Base Sequence; Bicuculline - pharmacology; Bridged Bicyclo Compounds - pharmacology; Bridged Bicyclo Compounds, Heterocyclic; chlorides; Cloning, Molecular; Complementary DNA; Convulsants - pharmacology; DNA Primers; DNA, Complementary - analysis; Drosophila; Drosophila melanogaster; Drosophila melanogaster - genetics; Drosophila melanogaster - metabolism; electrophysiology; Exons; Female; Flunitrazepam - pharmacology; GABA receptors; gamma-aminobutyric acid; gamma-Aminobutyric Acid - pharmacology; genbank/u02042; Gene Expression; Invertebrates; ion transport; Macromolecular Substances; Molecular Sequence Data; Muscimol - pharmacology; nucleotide sequences; Oocytes; Oocytes - drug effects; Oocytes - physiology; Pentobarbital - pharmacology; Pharmacology; Picrotoxin - pharmacology; Polymerase Chain Reaction; Receptors; Receptors, GABA - biosynthesis; Receptors, GABA - physiology; Receptors, GABA-A - physiology; Transcription, Genetic; Vertebrates; Xenopus laevis
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.91.13.6069

A cDNA encoding a functional gamma-aminobutyric (GABA)-activated Cl(-1) channel has been isolated from an adult Drosophila head cDNA library. When expressed in Xenopus laevis oocytes, the subunit functions efficiently, presumably as a homooligomeric complex and is activated by GABA or muscimol. GABA-evoked currents are highly sensitive to antagonism by picrotoxin but are insensitive to bicuculline, RU 5135, or zinc. Pentobarbitone greatly enhances GABA-evoked currents, whereas the neurosteroid 5 alpha-pregnan-3 alpha-ol-20-one demonstrates a large reduction in both the potency and effect when compared with its actions upon vertebrate GABA type A receptors. Although zinc-insensitive, the subunit is also insensitive to flunitrazepam. Hence, the GABA receptors formed by this subunit exhibit a unique pharmacology when compared with vertebrate GABA type A receptors or those composed of rho subunits. Because the receptor-channel complex functions as a homooligomer, this subunit may be of value in mutagenesis studies aiming to define drug-binding sites.