Figure 2.

AFM imaging of ASIC1a, anti-His₆ antibodies, and σ-1 receptors. (A) Low-magnification image of isolated ASIC1a. The arrow indicates a trimeric cluster of three equally sized particles, which is likely an ASIC trimer that has bound to the mica intact and then fallen apart during the drying process. A zoomed image of this cluster is shown at the bottom right of the panel. A shade-height scale is shown at the right. (B) Sections through the two particles indicated in A, taken at the positions indicated by the lines. The sections indicate that the shapes of the particles approximate that of a spherical cap. The calculated volumes of the particles are indicated. (C) Low-magnification image of anti-His₆ antibodies. A shade-height scale is shown at the right. (D) Frequency distribution of molecular volumes of anti-His₆ antibodies. The curve indicates the fitted Gaussian function. The mean of the distribution is indicated. (E) Low-magnification image of σ-1 receptors. A shade-height scale is shown at the right. (F) Frequency distribution of molecular volumes of σ-1 receptors. The curve indicates the fitted Gaussian function. The mean of the distribution is indicated.