Figure 1. Illustration of the maltose transport system in the periplasm.

The components are shown in different colors: maltose (red), maltoporin (green), apo MBP (orange), maltose-bound MBP (cyan), and ABC transporter (blue). Red arrows indicate the flow of maltose from the extracellular space into the cytoplasm, while black arrows indicate the signaling cycle for MBP. Peptidoglycan is represented with hexagons for the glycan chains, and lines for oligopeptide linkers between glycan chains.