Channel gating in the absence of agonist by a homooligomeric molluscan GABA receptor expressed inXenopus oocytes from a cloned cDNA
| Autor: | R. L. Ramsey, Robert J. Harvey, Narotam S. Bhandal, Mark G. Darlison, Peter N.R. Usherwood |
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| Rok vydání: | 1995 |
| Předmět: |
Agonist
medicine.medical_specialty DNA Complementary Patch-Clamp Techniques medicine.drug_class Population Biology Ion Channels gamma-Aminobutyric acid Xenopus laevis Cellular and Molecular Neuroscience chemistry.chemical_compound Receptors GABA Developmental Neuroscience GABA receptor Internal medicine medicine Animals Virulence Factors Bordetella Patch clamp Cloning Molecular education gamma-Aminobutyric Acid Ion channel Lymnaea education.field_of_study GABAA receptor Endocrinology chemistry Mollusca Oocytes Biophysics Cattle Female Ion Channel Gating medicine.drug Picrotoxin |
| Zdroj: | Invertebrate Neuroscience. 1:267-272 |
| ISSN: | 1439-1104 1354-2516 |
| DOI: | 10.1007/bf02211028 |
| Popis: | We have previously described the isolation of a complementary DNA (cDNA) from the freshwater mollusc Lymnaea stagnalis encoding a polypeptide that exhibits approximately 50% identity to the beta-subunits of vertebrate gamma-aminobutyric acid (GABA) type A (GABAA) receptor. When expressed in Xenopus laevis oocytes from in vitro-transcribed RNA, the snail subunit forms functional homo-oligomeric receptors possessing chloride-selective ion channels. In recordings from voltage-clamped oocytes held at -60 mV, GABA induced an inward current, whereas application of the chloride-channel blocker picrotoxin (in the absence of agonist) elicited an apparent outward current. Single channel recordings obtained from cell-attached patches have revealed a single population of approximately 20 pS channels, with an open probability greater than 90% (at a pipette potential of -100 mV) in the absence of GABA. The relationship between single channel current and pipette potential was linear over the studied range (-100 mV to +60 mV), but the open probability was less for hyperpolarizations than for depolarizations. The spontaneous channel openings were blocked by micromolar concentrations of picrotoxin. Functional hetero-oligomeric receptors were formed when the molluscan subunit was co-expressed in oocytes with the bovine GABAA receptor alpha 1-subunit, but the channels gated by these receptors did not open spontaneously. |
| Databáze: | OpenAIRE |
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