Comparisons of open-channel models. The radius of the protein at the position of the α-carbon atom of each residue is shown for the closed-state model of the protein (Chang et al., 1998) (black), the open-state model developed here (blue), the previously proposed open-state models (gray) of Meyer (2007) and (red) Sukharev et al. (2001b), and the SaMscL crystal structure (green) (Liu et al., 2009). The location of the EPR lower bound distance restraints included in the simulations is shown by the horizontal lines.