S. Yamaoka et al., COMPLEMENTATION CLONING OF NEMO, A COMPONENT OF THE I-KAPPA-B KINASE COMPLEX ESSENTIAL FOR NF-KAPPA-B ACTIVATION, Cell, 93(7), 1998, pp. 1231-1240
We have characterized a flat cellular variant of HTLV-1 Tax-transforme
d rat fibroblasts, 5R, which is unresponsive to all tested NF-kappa B
activating stimuli, and we report here its genetic complementation. Th
e recovered full-length cDNA encodes a 48 kDa protein, NEMO (NF-kappa
B Essential MOdulator), which contains a putative leucine zipper motif
. This protein is absent from 5R cells, is part of the high molecular
weight I kappa B kinase complex, and is required for its formation. In
vitro, NEMO can homodimerize and directly interacts with IKK-2. The N
EMO cDNA was also able to complement another NF-kappa B-unresponsive c
ell line, 1.3E2, in which the protein is also absent, allowing us to d
emonstrate that this factor is required not only for Tax but also for
LPS, PMA, and IL-1 stimulation of NF-kappa B activity.