Ultrastructural deformation studies on biological membranes

The ultrastructural deformation technique has been used to study various membranes, including several claimed to show subunit structure. With localized deformation fibers ca. 100-300 A in diameter and up to 4,000 A long were found extending across the cracks parallel to the draw direction in all membranes. Lipid extraction and proteolytic enzyme (papain) treatment of membranes has shown that the fibers are protein in nature. Deformation of membranes while still wet showed no significant change in the appearance of the fibers compared with those obtained from deformation of membranes after air drying, indicating that formation of fibers is not an artifact due to dehydration. There must be extensive interaction between the protein molecules and thus we indicate that the results do not agree with current suggestions that membranes are composed of individual protein subunits immersed in a lipid bilayer.