Fig. 1. Primary and secondary structural features of the CNBD. (A) ClustalW multiple sequence alignment of the CNBD of HERG with respect to that of the bacterial transcription factor (CAP), HCN2, KAT1 and ERG3 channels. Regions of secondary structures of CAP (Weber and Steitz, 1987) are indicated at the top and applied to the alignment of HCN2 (Zagotta et al., 2003). White arrows point to LQT2 missense mutations that fall within the putative CNBD of HERG at indicated residues. Black and gray arrows indicate residues of ERG3 and HCN2, respectively, that have been mutated in this study.