Previous model of the membrane topology of the T-domain in the open-channel state. The numbered residues in the main figure are those identified as being on either the cis or trans side by Senzel et al. (1998, 2000) or Gordon and Finkelstein (2001). Helices are not drawn to scale. (Inset) The amino-acid sequence of the segment from residue 294 to 320, whose ends were located on the cis side by Senzel et al. (2000). Residues with ionizable side chains are shown in bold type. The shaded boxes indicate α helices from the aqueous crystal structure (Bennett et al., 1994).