Fig. 1.

Structural features of the Sec translocon. (Left) The translocon is viewed from within the plane of the membrane, with the pore residues shown in orange and the plug moiety shown in red. The schematic illustrates the pore-plug displacement that is needed to allow for protein translocation via the channel. (Right) The translocon is viewed from outside the membrane on the cytosolic side, with the pore and plug colored as before and with the TM2b and TM7 helices that form the lateral gate shown in green. The schematic illustrates the lateral gate motion that opens the interior of the translocon to the membrane.