... conformations, in solution,membrane-bound, and membrane-inserted, stabilizespartially unfolded states of the C domain. In doing so,the T domain favors membrane binding and mem-brane penetration of the ... the A chain, correspondingto the catalytic (C) domain, and the B chain, corre-sponding to the translocation (T) and receptor-bindingdomains. The C and T domains remain covalentlylinked by ... lipidbilayer.ResultsRecombinant proteinsFive recombinant proteins were used in this study: C and T, corresponding to the isolated C and T domains,CT, corresponding to a truncated diphtheria toxinlacking the R domain,...