Figure 4.

Absence of the plug enhances the interaction of PpiD with the lateral gate and the SecY channel interior. A, cartoon showing the structure of the SecYEG complex (PDB 46VM). The positions where pBpa was inserted are indicated. B, in vivo cross-linking of BL21 cells expressing SecYEG with pBpa inserted at either position Ile-91 (TM2b, lateral gate), Ile-191 (TM5, channel), or Phe-278 (TM3, channel). When indicated, the plug domain of SecY was deleted. Samples were processed as described in the legend to Fig. 3 and decorated with either α-PpiD (B) or α-YidC antibodies (C). The lower part of the membrane was decorated with α-SecY antibodies.