Membrane isolation on polylysine-coated glass beads. Asymmetry of bound membrane.

Erythrocyte membranes isolated on polylysine-coated glass beads exhibit many of the properties of the native membrane. Gel electrophoresis indicates that all major protein components of the membrane are retained during membrane isolation. The membrane integrity and accessibility of selected components was tested using non-penetrating probes. In general, membranes on beads displayed accessibility properties typical of inside-out vesicles. The accessibility of membrane acetylcholinesterase to assay reagents, as well as membrane accessibility to the actions of neuraminidase, trypsin and galactose oxidase-NaB3H4 demonstrated that the protoplasmic surface of membrane isolated on beads was exposed, while the extracellular surface was inaccessible. The differential accessibility of the membrane surfaces demonstrates the feasibility of investigating asymmetry of membranes isolated on cationic glass beads.