Model for the functional separation of DegP, YcaL, and BepA. DegP degrades LptD that misfolds in the periplasm, while YcaL degrades substrate that is engaged with the Bam complex but has not yet formed a partial barrel (Bam-associated). BepA degrades LptD substrate that has formed a partial barrel around LptE and is still bound to the Bam complex (partial barrel). D, E, and B, BamD, BamE, and BamB, respectively.