Fig. 3.

Detailed structure of the SARS-CoV spike protein fusion core and OXO motifs in HR2 regions.A, surface map showing the hydrophobic grooves on the surface of the central coiled coil (right side). Three HR2 helices pack against the hydrophobic grooves in an oblique antiparallel manner (left side). The helical regions and extended regions in HR2 helices could be observed clearly, and the boundaries of these regions are marked. B, OXO motifs in HR2 regions of SARS-CoV spike protein fusion core structure. The enlarged images show two regions containing OXO motifs. The hydrophobic residues in these motifs all pack against the hydrophobic grooves on the surface of three HR1 helices.