Figure 1.

The structures of LPS and LBP. (a) Simplified structure of LPS from Gram-negative bacteria. The immunostimulatory lipid A is bound to a conserved inner core of sugars such as Kdo, which is bound in turn to a more variable outer core of common hexose sugars (eg glucose and galactose). The highly diverse O-antigen at the distal region of the LPS molecule is composed of repeated units of common hexose sugars. Rough-type LPS lacks an O-antigen. (b) Crystal structure of LBP (Protein Data Bank: 4M4D). The N-terminal portion is the main binding sites for lipid A, with the C-terminal involved in LPS transfer.