We then used CDD (Marchler-Bauer et al, 2009 ) to gather a representative set of structures containing an Ig-like fold domain (2cxk, 2as5, 1vkx, 1imh, 1ttu, 1cyg, 1clu, 7cgt, 1qhp, 1uad, 2uzx, 1gji, 2... 2t, 1a3q, 2yrp, 1kcl and 1nfk), which were structurally superposed using Swiss-PdbViewer (Guex & Peitsch, 1997 ).