||P.1 left column bottom paragraph: "The cell envelope surrounds the cytoplasm and consists of the plasma membrane (PM) and outer membrane (OM) flanking the periplasm [ref 6]. Figure 1 (left) shows the distribution of proteins in the different cell envelope compartments, associated and extracellular proteins (for the complete topological curation of E. coli proteins, see STEPdb (http://www.stepdb.eu)). Integral plasma membrane proteins (PMPs) are embedded in the PM—a ∼6-nm-thick phospholipid bilayer containing mostly phosphatidylethanolamine, phosphatidylglycerol and cardiolipin—via hydrophobic transmembrane α-helices of ∼20 amino acids. (Fig. 1, B). Some cytoplasmic proteins [refs 7,8] can also peripherally associate with the PM (Fig. 1, F1). The periplasm is 10–25-nm wide and contains peptidoglycan, a porous polymer that maintains bacterial shape and connects to the membranes via lipoproteins [refs 6,9]."