Fig. 7: Model for translocation of CDTa.

The illustrated protomers of CDTb-pore are equivalent to subunits C (left) and F (right). a CDTb-pore before CDTa binding. NSS-loops are shown in ‘in’ and ‘out’ states. b Single CDTa bound to CDTb-pore. c Unfolded CDTa also shown in Fig.6. CDTa tilting pushes the N-terminus of CDTa, causing partial unfolding and tilting of the N-terminal α-helix. d Unfolded CDTa translocates via the ϕ-clamp, using a ΔpH-driven Brownian ratchet mechanism, though the model is still an open question.