The Importance of Being Cleaved Karen S. Jakes  Molecular Cell  Volume 8, Issue 1, Pages 4-6 (July 2001) DOI: 10.1016/S1097-2765(01)00290-8

Figure 1 Schematic Drawing of the Pathways for Killing E. coli by Colicins B and D Both colicins are drawn with long coiled-coil receptor binding (dark blue) domains by analogy to the only reported structure solved for a whole colicin, Ia (Wiener et al., 1997). The receptor for both colicins, FepA (medium green), is shown in the outer membrane interacting with a turn in the R domain of both colicins. The R domains are long enough to span the periplasm, as shown. The translocation (T) domain (light blue) is known to interact with the TonB protein (light green), which is anchored in the inner membrane and can reach the outer membrane; ExbB and D (patterned light green) are inner membrane proteins that extend into the periplasm (Braun et al., 1994). Immunity protein (yellow) is shown coming off the colicin D complex in the periplasm. It is not known when that occurs, but it must be before LepB (dark green) cuts (scissors) colicin D just upstream of its catalytic (C) (red) domain (Zamaroczy et al., 2001). Colicin B does not have a bound immunity protein; its C domain makes a channel in the inner membrane Molecular Cell 2001 8, 4-6DOI: (10.1016/S1097-2765(01)00290-8)