Figure 4.

MyD88-S inhibits TLR signaling by preventing phosphorylation of IRAK1. Upon LPS stimulation, TLR4 recruits MyD88-L to the complex. MyD88-L in turn recruits IRAK4 and IRAK1. IRAK4 phosphorylates IRAK1, and IRAK1 auto-phosphorylates itself. MyD88-S is able to interact with TLR4 and IRAK1 but not IRAK4. Thus, MyD88-S prevents IRAK1 phosphorylation. For simplicity, not every protein in the signaling complex is depicted. Moreover, this signaling complex contains multiple copies of each peptide; for simplicity, only a single copy of each peptide is depicted in the diagram. Figure created with BioRender.com.