Fig. 4. The pre- and post-fusion conformations of paramyxovirus F glycoproteins.
Substantial structural rearrangements occur in the progression from pre-fusion to post-fusion F glycoprotein conformations. Several domains are distinguished by color including the large HR1-containing region (magenta) and the HR2 domain (blue). In the pre-fusion structure from PIV5 (A), a trimeric stabilization domain was added to support crystallization (grey). The six-helix bundle conformation is apparent in the hPIV3 structure (B). This figure was adapted from (111). The PDB codes for A and B are 2B9B and 1ZTM, respectively (111, 119).