Membranes of animal cells. I. Methods of isolation of the surface membrane

Procedures have been devised for the isolation of the surface membranes of mouse fibroblasts (L cell) and a variety of other cells. The surface membranes are stabilized by various reagents in a hypotonic solution and are then removed intact or as large fragments with a Dounce homogenizer. The membranes are purified by differential centrifugation on solutions of sucrose or glycerol or on a column of fine glass beads. A trilaminar pattern can be seen in thin sections of the membrane in the electron microscope. Sufficient material can be conveniently obtained for chemical analyses.