IRAK

Interleukin-1 receptor-associated kinase (IRAK) is first described as a signal transducer for the proinflammatory cytokine IL-1 and is later implicated in signal transduction of other members of the Toll-like receptor (TLR)/IL-1R family. Four different IRAK-like molecules have been identified: two active kinases, IRAK-1 and IRAK-4, and two inactive kinases, IRAK-2 and IRAK-M. All IRAKs mediate activation of NF-κB and MAPK pathways. IRAKs are protein kinases involved in signalling innate immune responses from TLRs. After TLR-4 and TLR-2 recognize pathogen-associated molecular patterns, such as LPS and peptidoglycan, all IRAK members form multimeric receptor complexes.

IRAKs are essential signaling intermediates in the TLR/IL-1R pathway to both IKK and MAPKs activation. These two pathways are central to the activation of several transcription factors, including NF-κB and AP-1, which contribute to the establishment of an immune response.