HTScan^® IKKε Kinase Assay Kit #7556

The NF-κB/Rel transcription factors are present in the cytosol in an inactive state, complexed with the inhibitory IκB proteins (1-3). Most agents that activate NF-κB do so through a common pathway based on phosphorylation-induced, proteasome-mediated degradation of IκB (3-7). The key regulatory step in this pathway involves activation of a high molecular weight IκB kinase (IKK) complex whose catalysis is generally carried out by three tightly associated IKK subunits. IKKα and IKKβ serve as the catalytic subunits of the kinase and IKKγ serves as the regulatory subunit (8,9). Activation of IKK depends upon phosphorylation at Ser177 and Ser181 in the activation loop of IKKβ (Ser176 and Ser180 in IKKα), which causes conformational changes, resulting in kinase activation (10-13).
Recently, two homologs of IKKalpha and IKKbeta have been described, called IKKepsilon (also known as IKK-i) and TBK-1 (also known as T2K or NAK), and activation of either of these kinases results in NFkappaB activation. The kinase domain of IKKepsilon is located in its amino-terminus, which shares 30% sequence homology with both IKKalpha and IKKbeta. IKKepsilon is expressed predominantly in immune cells, and may play a special role in the immune response (14-18).