Fig. 1.

Structure of the hPIV3 solF0 protein. (A) Schematic of the domain structure of the hPIV3 solF0 protein. Domain regions are indicated with hPIV3 sequence numbers shown below and with colors corresponding to those used in Fig. 1D.(B) Ribbon diagram of the hPIV3 solF0 trimer. The three chains are colored similarly from blue (N terminus) to red (C terminus). Residues 95-135 are disordered in all chains. Residue 94 is labeled in one chain and residues 136-140 at the base of the stalk are ordered in one chain because of crystal packing interactions. (C) Surface representation of the solF0 trimer. Each chain is a different color and domains I-III and HRB for one chain (yellow) are indicated by the DI, DII, DIII, and HRB labels. One radial channel is readily apparent below domains I and II of the yellow chain and above domain III of the red chain. (D) Ribbon diagram of the solF0 protein monomer colored by domain. The direct distance within one monomer between residue 94 at the end of HRC and residue 142 at the base of the stalk region is 122 Å. (E) Ribbon diagram of the monomer rotated by 90°, indicating the width and height of the solF0 monomer. An arrow at the C terminus of the HRB segment points toward the likely position of the TM anchor domain that would be present in the full-length protein.