FIG. 3.

PKR is an intermediary component in TLR signaling. PKR is implicated in the LPS/TLR4-mediated pathway probably recruited by the TIRAP complex. PKR is also involved during the dsRNA/TLR3 pathway, recruited by a TAK1-containing complex. Several proteins act downstream from PKR, such as TRAF6, which has been identified downstream of PKR in the signaling cascades triggered by TLR3 and TLR4. Moreover, TRAF3 is also involved in PKR downstream events during the activation of TLR3. The activation of these pathways in turn triggers the induction of proinflammatory cytokines. RIGI/MDA5 in response to dsRNA signaling is indicated.