Cloning and functional expression of a Drosophila gamma-aminobutyric acid receptor.
A cDNA encoding a functional gamma-aminobutyric (GABA)-activated Cl- 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 maximal 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.
CoCensys, Inc., Irvine, CA 92718.
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Chen
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Belelli
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Lambert
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Peters
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Reyes
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Lan
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001640:Bicuculline / Q000494:pharmacology; D001643:Bridged Bicyclo Compounds / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003001:Cloning, Molecular; D003292:Convulsants / Q000494:pharmacology; D017931:DNA Primers; D018076:DNA, Complementary / Q000032:analysis; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005445:Flunitrazepam / Q000494:pharmacology; D015870:Gene Expression; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009118:Muscimol / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000502:physiology; D010424:Pentobarbital / Q000494:pharmacology; D010852:Picrotoxin / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D018079:Receptors, GABA / Q000096:biosynthesis / Q000502:physiology*; D011963:Receptors, GABA-A / Q000502:physiology*; D014158:Transcription, Genetic; D014982:Xenopus laevis; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D001640:Bicuculline; D001643:Bridged Bicyclo Compounds; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003292:Convulsants; D017931:DNA Primers; D018076:DNA, Complementary; D005445:Flunitrazepam; D046911:Macromolecular Substances; D009118:Muscimol; D010424:Pentobarbital; D010852:Picrotoxin; D018079:Receptors, GABA; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; C037476:tert-butylbicyclophosphorothionate