To further the understanding of functional Î±6Î±5*- nicotinic acetylcholine receptors (nAChR; the asterisk (*) indicates known or possible presence of other subunits), we have heterologously expressed in oocytes different, mouse or human, nAChR subunit combinations. Coexpression with wild-type Î±5 subunits or chimeric Î±5/Î²3 subunits (in which the human Î±5 subunit N-terminal, extracellular domain is linked to the remaining domains of the human Î²3 subunit) almost completely abolishes the very small amount of function seen for Î±6Î²4*-nAChR and does not induce function of Î±6Î²2*-nAChR. Coexpression with human Î±5 V9,S subunits bearing a valine 290 to serine mutation in the 9â€² position of the second transmembrane domain does not rescue the function of Î±6Î²4*-nAChR or induce function of Î±6Î²2*-nAChR. However, coexpression with mutant chimeric Î±5/Î²3 V9,S subunits has a gain-of-function effect (higher functional expression and agonist sensitivity and spontaneous opening inhibited by mecamylamine) on Î±6Î²4*- nAChR. Moreover, N143D + M145V mutations in the Î±6 subunit N-terminal domain enable Î±5/Î²3 V9,S subunits to have a gain-of-function effect on Î±6Î²2*-nAChR. nAChR containing chimeric Î±6/Î±3 subunits plus either Î²2 or Î²4 subunits have some function that is modulated in the presence of Î±5 or Î±5/Î²3 subunits. Coexpression with Î±5/Î²3 V9,S subunits has a gain-of-function effect more pronounced than that in the presence of Î±5 V9,S subunits. Gain-of-function effects are dependent, sometimes subtly, on the nature and apparently the extracellular, cytoplasmic, and/or transmembrane domain topology of partner subunits. These studies yield insight into assembly of functional Î±6Î±5*-nAChR and provide tools for development of Î±6*- nAChR-selective ligands that could be important in the treatment of nicotine dependence, and perhaps other neurological diseases. Â© 2011 by The American Society for Biochemistry and Molecular Biology, Inc.
Journal of Biological Chemistry
Digital Object Identifier (DOI)
Dash, Bhagirathi; Chang, Yongchang; and Lukas, Ronald J., "Reporter Mutation Studies Show That Nicotinic Acetylcholine Receptor (Nachr) Î±5 Subunits And/Or Variants Modulate Function Of Î±6*-Nachr" (2011). Neurobiology. 270.