I kappa B kinase-alpha and -beta genes are coexpressed in adult and embryonic tissues but localized to different human chromosomes

Activation of the transcription factor nuclear factor kappa B (NF-kappa B) is regulated by phosphorylation, ubiquitination, and degradation of its inh ibitory factor I kappa B. Very recently, two closely related serine/threoni ne kinases have been identified as I kappa B kinases which are essential fo r I kappa B phosphorylation and NF-kappa B activation. Here, we isolated th e full-length human cDNA clones encoding these two I kappa B kinases, IKK-a lpha and IKK-beta. Both polypeptides contain a conserved amino-terminal kin ase domain, a leucine zipper motif and a helix-loop-helix domain at their c arboxyl terminus. We showed that IKK-alpha and IKK-beta were coexpressed in most human adult tissues as well as in different developmental stages of m ouse embryos, suggesting that they may cooperate in the cells. The IKK-alph a and IKK-beta genes are distinct but evolutionarily conserved. Moreover, t he IKK-alpha gene locus was mapped to human chromosome 10q24, whereas the I KK-beta gene locus was localized to human chromosome 8p11.2. These results indicated that both genes are not clustered on the same chromosome; neverth eless, both genes may be still regulated similarly during development and i n adult tissues. (C) 1998 Published by Elsevier Science B.V. All rights res erved.