Catalytic domain of the Serine/Threonine kinase, Inhibitor of Nuclear Factor-KappaB Kinase (IKK) beta
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. IKKbeta is involved in the classical pathway of regulating Nuclear Factor-KappaB (NF-kB) proteins, a family of transcription factors which are critical in many cellular functions including inflammatory responses, immune development, cell survival, and cell proliferation, among others. The classical pathway regulates the majority of genes activated by NF-kB including those encoding cytokines, chemokines, leukocyte adhesion molecules, and anti-apoptotic factors. It involves NEMO (NF-kB Essential MOdulator)- and IKKbeta-dependent phosphorylation and degradation of the Inhibitor of NF-kB (IkB), which liberates NF-kB dimers (typified by the p50-p65 heterodimer) from an inactive IkB/dimeric NF-kB complex, enabling them to migrate to the nucleus where they regulate gene transcription. The IKKbeta subfamily is part of a larger superfamily that includes the catalytic domains of other protein STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.
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