A, ColE9 residues 3-67 of the IUTD in the partial translocon structure pass through OmpF subunit 2 and then back up into subunit 1. As a result, OBS1 (gold) docks within subunit 1 and OBS2 (orange) within subunit 2. The ColE9 TBE motif (pink) interacts with TolB and is positioned below subunit 2, above which the ColE9 T-domain is located. 