Figure 5.

Conformation of Ribosome-Bound Sec61α

(A) Overview of the lateral gate of the ribosome-bound Sec61α in red, compared to the isolated crystal structure of the archaeal SecY in gray (Park et al., 2014).

(B) Cytosolic loop 6/7 shifts by 11 Å relative to the the archaeal SecY structure.

(C) Cytosolic loop 8/9 shifts by 6 Å relative to the bacterial SecY structure shown in pink (Tsukazaki et al., 2008). The bacterial structure is used for comparison here because loop 8/9 is disordered in the archaeal structure.

(D) Close-up of the lateral gate (helices 2 and 3 with helices 7 and 8), highlighting the opening of the cytosolic region between helices 8 and 2 in the ribosome-bound state.

(E) Close-up of the plug region, which is unaltered in the ribosome-bound state.

(F) Comparison of the lateral gate in the Sec61-ribosome structure relative to that observed in the SecY-SecA complex (light blue; Zimmer et al., 2008).