Channel gating in the absence of agonist by a homooligomeric molluscan GABA receptor expressed in Xenopus oocytes from a cloned cDNA

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Channel gating in the absence of agonist by a homooligomeric molluscan GABA receptor expressed in Xenopus oocytes from a cloned cDNA

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Title: Channel gating in the absence of agonist by a homooligomeric molluscan GABA receptor expressed in Xenopus oocytes from a cloned cDNA
Author/Creator: Bhandal, N S | Ramsey, R L | Harvey, Robert J | Darlison, M G | Usherwood, P N R
Description: We have previously described the isolation of a complementary DNA (cDNA) from the freshwater mollusc Lymnaea stagnalis encoding a polypeptide that exhibits ∼50% identity to the ß-subunits of vertebrate γ-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 ∼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 α1-subunit, but the channels gated by these receptors did not open spontaneously. © 1995 Sheffield Academic Press.
Relation: Invertebrate Neuroscience / Vol. 1, No. 3, pp.267-272
Relation: http://dx.doi.org/10.1007/BF02211028
Year: 1995
Publisher: Springer
Subject: FoR 0608 (Zoology) | FoR 1109 (Neurosciences) | GABA receptors | mollusc (Lymnaea stagnalis) | picrotoxin | single-channel recordings | spontaneous channel openings | Xenopus oocytes

Resource Type: Journal Article
Identifier: ISSN: 1354-2516
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