Cover photograph (Copyright © 2007, American Society for Microbiology. All Rights Reserved.): The Escherichia coli DegP protein is an example of a self-compartmentalized protease because the active sites are located in a central cavity that is only accessible laterally. It has been hypothesized that unfolded polypeptides are threaded in an extended conformation into the cage to access the proteolytic sites. However, the presence of an enclosed cage is not essential for the chaperone and protease activities of DegP. The image is a close-up view of the inner cavity of DegP, and it was obtained by limiting the resolution of the atomic structure (PDB ID: 1KY9) to 10 Å. The map was displayed as a surface-rendering representation with the UCSF-Chimera program. (See related article on page 706.)