Fig. 4.

A two-step conformational adaptation of apoE3 upon lipoprotein binding. ApoE3 structures are shown in ribbons and the colors are coded the same as Fig. 2. The helices are labeled respectively. This two-step conformation adaptation of apoE3 upon lipoprotein association follows a specific and precise self-modulation pathway, which is regulated by the special topology of lipid-free apoE3 structure. We assume that there is no major change of the helix locations in apoE3 during lipid-binding.