Stereo-view of hIgG2 3D model at 1.78 nm resolution.

<p>From top to bottom, the model is rotated 90° clockwise along the vertical axis of Fc. The model is oriented so that Fab subunits are on top. Fab-1 (see text for details) is at top left. The density threshold cutoff determined in EMAN is based on a molecular mass of 160 kDa and a protein density of 1.35 g/cm³. Weak electron densities, which connect parts of the molecule, are not visible at this threshold.