The 3.3 Å Crystal Structure of IpgC10-155 Reveals a SycD-like Dimerization Interface. (A) Refined asymmetric unit of the IpgC10-155 crystal. The 18 distinct polypeptides are colored individually; helices are depicted as cylinders for clarity. The boundaries of the primitive monoclinic cell are shown as a green box. (B) Representative model-to-map correlation for an IpgC10-155 dimer pair; note that this same pair is colored identically to and further analyzed in panel C. 2Fo-Fc weighted electron density (contoured at 1.2 σ) is drawn as a blue cage. (C) Detailed stereoscopic view of the dimerization interface observed in IpgC10-155. The two monomers are colored in blue and orange, respectively, while the intercalated network of aromatic sidechains is shown in magenta. (D) Orthogonal views of superposition by Local-Global Alignment for the proposed IpgC1-151 dimer (magenta) with that of IpgC10-155 (blue). (E) Orthogonal views of superposition by Local-Global Alignment for the proposed SycD21-163 dimer (orange) with that of IpgC10-155 (blue) dimer structure. Additional quantitative descriptions of the quality of the superpositions shown in panels D and E may be found in Table 2.