Structure of the gp5-gp27 complex. A, The gp5-gp27 trimer is shown as a ribbon diagram in which each chain is shown in a different color. B, Domains of gp27. The two homologous domains are colored in light green and cyan. C, Side and end on views of the C-terminal β-helical domain of gp5. D, The pseudohexameric feature of the gp27 trimer is outlined with a hexamer (domains are colored as in B).