Structures of the gp18 deletion mutants reprinted from . A, A ribbon diagram of the gp18PR mutant. The N terminus is shown in blue, the C terminus in red and the intermediate residues change color in spectral order. B, C, A ribbon diagram of the gp18M mutant (¾ of the total protein length). The three domains are shown in blue (domain I), olive green (domain II) and orange red (domain III); the β-hairpin (residues 454-470) and the last 14 C-terminal residues of gp18M are shown in cyan. D, Domain positions on the amino acid sequence, using the same color scheme as in (B) and (C). Brown indicates the part of gp18 for which the structure remains unknown.