Electron-irradiation-induced flattening of negatively stained 2D protein crystals

The thickness of negatively stained 2D crystalline arrays of the bladder membrane does not vary significantly during air drying and exposure to high vacuum. High-dose electron irradiation reduces the thickness to about 60% of the native value. These results, together with the fact that the same behaviour has been observed on another 2D system (gap junctions), indicate that the flattening induced by an electron beam on 2D crystals may be general. The implications for 3D reconstruction of negatively stained objects are discussed.