Figure S3.

Protruding Model of NPC1-C, Related to Figure 1

We cannot see the density for both ends immediately adjacent to the TM segments. The missing residues (in dash lines) of both the N-terminal and C-terminal could be flexible loops, which will not make the visible domain C structure to be tightly attached to the endosomal membrane. It is assumed that, with these flexible N-terminal and C-terminal loops, the domain C can protrude from the endosomal membrane and be easily bound by the primed GP molecule.