Ikbkb
Developmental stage
While it is expressed ubiquitously throughout the mouse embryo, at 9.5 dpc its expression begins to be localized to the brain, neural ganglia, neural tube, and in liver at 12.5 dpc. At 15.5 dpc, the expression is further restricted to specific tissues of the embryo.
Domain
The kinase domain is located in the N-terminal region. The leucine zipper is important to allow homo- and hetero-dimerization. At the C-terminal region is located the region responsible for the interaction with NEMO/IKBKG.
Function
Serine kinase that plays an essential role in the NF-kappa-B signaling pathway which is activated by multiple stimuli such as inflammatory cytokines, bacterial or viral products, DNA damages or other cellular stresses (By similarity). Acts as a part of the canonical IKK complex in the conventional pathway of NF-kappa-B activation (By similarity). Phosphorylates inhibitors of NF-kappa-B on 2 critical serine residues (By similarity). These modifications allow polyubiquitination of the inhibitors and subsequent degradation by the proteasome (By similarity). In turn, free NF-kappa-B is translocated into the nucleus and activates the transcription of hundreds of genes involved in immune response, growth control, or protection against apoptosis (By similarity). In addition to the NF-kappa-B inhibitors, phosphorylates several other components of the signaling pathway including NEMO/IKBKG, NF-kappa-B subunits RELA and NFKB1, as well as IKK-related kinases TBK1 and IKBKE (By similarity). IKK-related kinase phosphorylations may prevent the overproduction of inflammatory mediators since they exert a negative regulation on canonical IKKs (By similarity). Phosphorylates FOXO3, mediating the TNF-dependent inactivation of this pro-apoptotic transcription factor (By similarity). Also phosphorylates other substrates including NAA10, NCOA3, BCL10 and IRS1 (By similarity). Phosphorylates RIPK1 at 'Ser-25' which represses its kinase activity and consequently prevents TNF-mediated RIPK1-dependent cell death (PubMed:30988283). Phosphorylates the C-terminus of IRF5, stimulating IRF5 homodimerization and translocation into the nucleus (PubMed:25326420). Following bacterial lipopolysaccharide (LPS)-induced TLR4 endocytosis, phosphorylates STAT1 at 'Thr-748' which restricts interferon signaling and anti-inflammatory responses and promotes innate inflammatory responses (PubMed:38621137). IKBKB-mediated phosphorylation of STAT1 at 'Thr-748' promotes binding of STAT1 to the ARID5A promoter, resulting in transcriptional activation of ARID5A and subsequent ARID5A-mediated stabilization of IL6 (By similarity). It also promotes binding of STAT1 to the IL12B promoter and activation of IL12B transcription (By similarity).
Post-translational modifications
Upon cytokine stimulation, phosphorylated on Ser-177 and Ser-181 by MEKK1 and/or MAP3K14/NIK as well as TBK1 and PRKCZ; which enhances activity. Phosphorylated by MAP3K7/TAK1 in response to NOD1 and NOD2 signaling, promoting activation and phosphorylation of NF-kappa-B inhibitors, leading to NF-kappa-B activation. Once activated, autophosphorylates on the C-terminal serine cluster; which decreases activity and prevents prolonged activation of the inflammatory response. Phosphorylated by the IKK-related kinases TBK1 and IKBKE, which is associated with reduced CHUK/IKKA and IKBKB activity and NF-kappa-B-dependent gene transcription. Dephosphorylated at Ser-177 and Ser-181 by PPM1A and PPM1B.
Ubiquitinated. Monoubiquitination involves TRIM21 that leads to inhibition of Tax-induced NF-kappa-B signaling. 'Ser-163' may not serve as a monoubiquitination site. Ubiquitination on 'Ser-163' may modulate phosphorylation on C-terminal serine residues.
Hydroxylated by PHD1/EGLN2, loss of hydroxylation under hypoxic conditions results in activation of NF-kappa-B.
Sequence Similarities
Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. I-kappa-B kinase subfamily.
Tissue Specificity
Detected in heart (at protein level) (PubMed:23090968). Expressed in liver, kidney and spleen.
Cellular localization
- Cytoplasm
- Nucleus
- Membrane raft
- Colocalized with DPP4 in membrane rafts.
Alternative names
Ikkb, Ikbkb, Inhibitor of nuclear factor kappa-B kinase subunit beta, I-kappa-B-kinase beta, IKK-B, IKK-beta, IkBKB, I-kappa-B kinase 2, Nuclear factor NF-kappa-B inhibitor kinase beta, Serine/threonine protein kinase IKBKB, IKK2, NFKBIKB