G protein-activated K+ channels: a reporter for rapid activation of G proteins by lysophosphatidic acid in Xenopus oocytes
- Itzhaki Van-Ham, Irit
- Peleg, Sagit
- Dascal, Nathan
- Shapira, Hagit
- Oron, Yoram
DOIAbstract
AbstractThreshold 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 Gαo/Gαo1 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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