Figure 7 - full size

 

Figure 7.
Figure 7. SV5 HN Tetramers
Active sites are marked by space-filling representations of the ligand sialyllactose. The four subunits are shown in different colors.
(A) Top view of the SV5 HN tetramer arrangement.
(B) Side view of the SV5 HN tetramer arrangement, with a 60 packing angle between dimers.
(C) Side view of the superimposed SV5 HN and NDV HN tetramers, showing a shift in dimer packing. SV5 HN is colored blue, and NDV HN is colored green.
(D) A model for HN tetramer rearrangement upon cell-surface receptor binding. The HN tetramer is primarily stabilized by the N-terminal stalk region and can interact with F. Sialic acid receptors are displayed at the cell surface, where binding of the individual HN NA domains could perturb the NA tetramer arrangement, consistent with the weak interactions between NA domains. Changes in the HN NA domain tetramer could affect F interactions and stimulate membrane fusion.

The above figure is reprinted by permission from Cell Press: Structure (2005, 13, 803-815) copyright 2005.