Spectral changes at the SF region underlying transitions between the putative resting/conductive and slow-inactivated states. CW spectra for Na_VSp1 at representative positions in the P2 helix (positions marked on the Na_VAb structure) reconstituted in asolectin (red) and DOTAP (cyan) and compared with Na_VSp1-P reconstituted in asolectin (black). A similarity of Na_VSp1-DOTAP and Na_VSp1-P–asolectin spectra is highlighted in the gray box.