G protein-activated K+ channels: a reporter for rapid activation of G proteins by lysophosphatidic acid in Xenopus oocytes |
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Authors: | Itzhaki Van-Ham Irit Peleg Sagit Dascal Nathan Shapira Hagit Oron Yoram |
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Institution: | Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel. |
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Abstract: | Threshold concentrations of lysophosphatidic acid (LPA) or acetylcholine (ACh) induce pertussis toxin (PTX)-sensitive rapid desensitization of responses to LPA in Xenopus oocytes. To demonstrate that threshold LPA] rapidly activates Gi/o proteins, we used the G protein-activated K+ channel (GIRK) as a reporter. Low LPA] induced IK+ in <3 s of the agonist addition with little or no activation of chloride current. Depletion of Galphao/Galphao1 each decreased the LPA-induced IK+ by approximately 40-50%, while PTX completely abolished it. This is the first direct evidence showing the activation of GIRK by LPA, and the involvement of G proteins of the Go family in rapid desensitization of LPA responses. |
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