PMID: 8454605Mar 25, 1993Paper

Transverse localization of the quinacrine binding site on the Torpedo acetylcholine receptor.

The Journal of Biological Chemistry
H R AriasD A Johnson

Abstract

We demonstrated previously that a phencyclidine-displaceable quinacrine binding site exists at the lipid-protein interface of the Torpedo acetylcholine receptor (AcChR) (Valenzuela, C. F., Kerr, J. A., and Johnson, D. A. (1992) J. Biol. Chem. 267, 8238-8244). In this manuscript, we assess (1) the transverse position of this site in the lipid bilayer by examining the ability of a series of paramagnetic n-doxyl stearates (n-SALs) and iodide to quench receptor-bound quinacrine and membrane-partitioned octadecyl rhodamine B (C18-Rho) fluorescence and (2) the stoichiometry of histrionicotoxin- or phencyclidine-displaceable quinacrine binding. Initial experiments established what fraction of the n-doxyl stearates partitioned into the membranes and that the n-doxyl stearates do not interfere with quinacrine binding to the receptor at the concentrations used in the quenching studies. The n-doxyl stearate quenching experiments indicated relatively small (< 2) differences between the n-doxyl stearates to quench receptor-bound quinacrine fluorescence, with a rank order of 7-SAL > or = 5-SAL > 12-SAL > 16-SAL. This contrasts with the n-doxyl stearate quenching of the membrane-partitioned C18-Rho which showed as much as an 8.6-fold differen...Continue Reading

Related Concepts

Related Feeds

ASBMB Publications

The American Society for Biochemistry and Molecular Biology (ASBMB) includes the Journal of Biological Chemistry, Molecular & Cellular Proteomics, and the Journal of Lipid Research. Discover the latest research from ASBMB here.