Elsevier

Neuroscience Research

Volume 26, Issue 3, November 1996, Pages 289-297
Neuroscience Research

Research report
G protein specificity of the muscarine-induced increase in an inward rectifier potassium current in AtT-20 cells

https://doi.org/10.1016/S0168-0102(96)01111-XGet rights and content

Abstract

Muscarine and somatostatin enhance an inward rectifier K+ conductance in the AtT-20 pituitary cell line. Both effects are abolished by pertussis toxin (PTX). To determine which PTX-sensitive G protein mediates these agonist effects, we made cDNAs encoding mutant PTX-insensitive G subtypes, in which the cysteine residue fourth from the C terminus was replaced with serine. The mutated cDNA was transfected into AtT-20 cells, resulting in stable cell lines overexpressing a G subtype. As controls, wild-type G cDNA was transfected into AtT-20 cells. The agonist-induced increase of the inward rectifier K+ conductance in the transfectants was examined with the whole-cell clamp method. Only in the cell lines into which the mutated (PTX-insensitive) Gi2α cDNA was transfected, did the muscarine response become PTX-insensitive, suggesting that Gi2 couples to the muscarinic receptor and enhances the activity of the inward rectifier K+ channel. However, PTX-insensitive somatostatin responses were not obtained in any of the cell lines transfected with a mutated G cDNA, suggesting either that none of the Gi subtypes is a transducer for the somatostatin effect or that the mutation prevents the coupling of the G to the somatostatin receptor.

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  • Cited by (0)

    1

    Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75235-9041.

    2

    Department of Biosciences, Faculty of Bioscience and Technology, Tokyo Institute of Technology, 4259 Nagatsuda, Midoriku, Yokohama, 226, Japan.

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