Freeze-fracture autoradiography of the red blood cell plasma membrane

A procedure for electron microscope autoradiography of red blood cell ghosts or their outer membrane leaflets is described: sheep erythrocytes, attached to positively charged mica, were either lysed and air-dried, or freeze-fractured "by hand" and freeze-dried. This was followed by shadowing and carbon replication; coating with photographic emulsion; exposure in darkness at 277 K; developing and fixation; carbon coating; floating off the mica and mounting on grids. Erythrocytes iodinated with 125I using the lactoperoxidase reaction were used as a test object. The efficiency of the procedure was found to be between 3.4% and 5.6%.