FIGURE 39.2. Activation of immune signaling by bacterial lipopolysaccharide (LPS).


Activation of immune signaling by bacterial lipopolysaccharide (LPS). LPS from the cell wall of Gram-negative bacteria is bound by the pattern-recognition molecule Toll-like receptor 4 (TLR4) in conjunction with the cell-surface receptor CD14. The binding of LPS leads to recruitment of the adaptor proteins MyD88 and IRAK to the cytoplasmic domain of TLR4. This complex initiates a signaling cascade of phosphorylation events through TRAF 6 and the kinase IκK. Finally, IκK phosphorylates IκB, an inhibitor bound to the transcription factor NF-κB. Phosphorylated IκB is degraded, releasing NF-κB, which migrates to the nucleus where it activates the transcription of proinflammatory genes. Similar signal transduction pathways are activated by Gram-positive cell wall constituents such as peptidoglycan and lipoteichoic acid via TLR2 or TLR6.

Download Teaching Slide (PPT, 257K)

From: Chapter 39, Bacterial and Viral Infections

Cover of Essentials of Glycobiology
Essentials of Glycobiology. 2nd edition.
Varki A, Cummings RD, Esko JD, et al., editors.
Cold Spring Harbor (NY): Cold Spring Harbor Laboratory Press; 2009.
Copyright © 2009, The Consortium of Glycobiology Editors, La Jolla, California.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.