A RESIDUE IN THE MIDDLE OF THE M2-M3 LOOP OF THE BETA(4) SUBUNIT SPECIFICALLY AFFECTS GATING OF NEURONAL NICOTINIC RECEPTORS

An aspartate residue in the M2-M3 loop of neuronal nicotinic receptor alpha(7) subunits is a major determinant of the channel functional res ponse. This residue is conserved in most beta(4) subunits, e.g. human and rat, but not in others, e.g. bovine, We have used these difference s to examine the mechanism by which this residue alters the functional properties of alpha(3)beta(4) receptors, Having ruled out an effect o n the macroscopic binding ability of the agonist, the level of recepto r expression, or the single channel conductance, the results suggest t hat receptors lacking that residue have a deficient coupling between b inding and gating, (C) 1998 Federation of European Biochemical Societi es.