Residues that Comprise the Head-to-Head Dimerization Interface in IpgC10-155 are Conserved among Class II Chaperones. The sequences of IpgC and its homologs were aligned using the ClustalW method and compared to the secondary structure elements of both the IpgC1-151  and the SycD21-163 crystal structures with Espript. Residue positions were numbered using the IpgC sequence as a reference. Identical residues are shown in cyan typeface, while similar residues (as judged by the BLOSUM62 substitution matrix) are shown in purple typeface. Residues at positions 46, 58, and 61 form "head-to-head" contacts in the crystal structure (see Figure 1C) and are denoted with a red star. Residues at positions 42 and 53 appear to form sidechain-to-sidechain hydrogen bonds and are denoted with an orange star.