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
(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: