Pro-inflammatory cytokines activate the transcription factor @entity2451 by stimulating the activity of a protein kinase that phosphorylates IkappaB, an inhibitor of @entity2451 , at sites that trigger its ubiquitination and degradation. This results in the nuclear translocation of freed @entity2451 dimers and the activation of transcription of target genes. Many of these target genes code for immunoregulatory proteins. A large, cytokine-responsive IkappaB kinase (IKK) complex has been purified and the genes encoding two of its subunits have been cloned. These subunits, @entity18159 and @entity15955 , are protein kinases whose function is needed for @entity2451 activation by pro-inflammatory stimuli. Here, by using a monoclonal antibody against @entity18159 , we purify the IKK complex to homogeneity from @entity1 cell lines. We find that IKK is composed of similar amounts of @entity18159 , @entity15955 and two other polypeptides, for which we obtained partial sequences. These polypeptides are differentially processed forms of a third subunit, @entity10190 . Molecular cloning and sequencing indicate that @entity10190 is composed of several potential coiled-coil motifs. @entity10190 interacts preferentially with @entity15955 and is required for the activation of the IKK complex. An @entity10190 @entity1473 -terminal truncation mutant that still binds @entity15955 blocks the activation of IKK and @entity2451 .

XXXX is an essential regulatory subunit of the IkappaB kinase complex.

@entity1 :: ('9606', 'Species') :: ['human'] @entity2451 :: ('4790', 'Gene') :: ['NF-kappaB'] @entity15955 :: ('3551', 'Gene') :: ['IKK-beta'] @entity10190 :: ('8517', 'Gene') :: ['IKK-gamma'] @entity18159 :: ('1147', 'Gene') :: ['IKK-alpha'] @entity1473 :: ('CHEBI:46883', 'Chemical') :: ['carboxy']
@entity10190 :: (8517,Gene) :: ['IKK-gamma']
