Distribution and stability of membrane proteins in lipid membranes on solid supports

Bacteriorhodopsin and the nicotinic acetylcholine receptor were biotinylate d and reconstituted in lipidic membranes on silicon supports by fusion with proteoliposomes. The presence and distribution of the proteins were studie d by binding with streptavidin. Radio-labelled streptavidin was employed fo r quantifying the amounts of protein remaining in the supported membranes a fter storage in buffer. The proteins within the membranes remained bound to the surface for weeks. The biological activity of reconstituted unlabelled receptor upon storage showed stability in membranes formed on silicon supp orts and a reduced stability when formed onto lipid monolayer covered suppo rts. Atomic force microscopy studies on preparations in liquid showed bilay er structures but also attached, partly fused liposomes and membrane partic les. In air, the surface was smoother and contained less of liposomes and m ore of stacked lipid layers. Preparations labelled with streptavidin conjug ated to colloidal gold and imaged in air showed the proteins individually d istributed, with no protein-rich patches or protein aggregates. (C) 2000 El sevier Science S.A. All rights reserved.