Chaperone Protein 14-3-3 And Protein Kinase A Increase The Relative Abundance Of Low Agonist Sensitivity Human Î±4Î²2 Nicotinic Acetylcholine Receptors In Xenopus Oocytes
Î±4 and Î²2 nicotinic acetylcholine (nACh) receptor subunits expressed heterologously in Xenopus oocytes assemble into a mixture of receptors with high and low agonist sensitivity whose relative abundance is influenced by the heteropentamer subunit ratio. We have found that inhibition of protein kinase A by KT5720 decreased maximal [3H]cytisine binding and acetylcholine (ACh)-induced current responses, and increased the relative proportion of Î±4Î²2 receptors with high agonist sensitivity. Mutation of serine 467, a putative protein kinase A substrate in a chaperone protein binding motif within the large cytoplasmic domain of the Î±4 subunit, to alanine or asparate decreased or increased, respectively, maximal [ 3H]cytisine binding and ACh response amplitude. Expression of Î±4S467A mutant subunits decreased steady levels of Î±4 and the relative proportion of Î±4Î²2 receptors with low agonist sensitivity, whilst expression of Î±4S467D increased steady levels of Î±4 and Î±4Î²2 receptors with low agonist sensitivity. Difopein, an inhibitor of chaperone 14-3-3 proteins, decreased [3H]cytisine binding and ACh responses and increased the proportion of Î±4Î²2 with high sensitivity to activation by ACh. Thus, post-translational modification affecting steady-state levels of Î±4 subunits provides a possible means for physiologically relevant, chaperone-mediated variation in the relative proportion of high and low agonist sensitivity Î±4Î²2 nACh receptors. Â© 2006 The Authors.
Journal of Neurochemistry
Digital Object Identifier (DOI)
Exley, Richard; Moroni, Mirko; Sasdelli, Federica; Houlihan, Lee M.; Lukas, Ronald J.; Sher, Emanuele; Zwart, Ruud; and Bermudez, Isabel, "Chaperone Protein 14-3-3 And Protein Kinase A Increase The Relative Abundance Of Low Agonist Sensitivity Human Î±4Î²2 Nicotinic Acetylcholine Receptors In Xenopus Oocytes" (2006). Neurobiology. 189.