Conserved Helix Loop Helix Ubiquitous Kinase (CHUK)

NFKB1 or NFKB2 is bound to REL, RELA , or RELB to form the NFKB complex. The NFKB complex is inhibited by I-kappa-B proteins (NFKBIA or NFKBIB), which inactivate NF-kappa-B by trapping it in the cytoplasm. Phosphorylation of serine residues on the I-kappa-B proteins by kinases (IKBKA or IKBKB) marks them for destruction via the ubiquitination pathway, thereby allowing activation of the NF-kappa-B complex.

CHUK contains a serine/threonine kinase domain; due to its ubiquitous expression in a broad array of tissues and high degree of conservation across species, it was designated CHUK for 'conserved helix-loop-helix ubiquitous kinase.' The multidomain polypeptide encoded by the CHUK gene also contains leucine zipper motifs.