Isolation, sequence, and chromosomal localisation of the human IkappaBR gene (NFKBIL2)

The inhibitors of NF-kappaB (IkappaBs) play an important role in the regulation of the NF-kappaB pathway. IkappaBR (for IkappaB-Related) is proposed to be a novel member of this family. We report the cloning and characterization of the region of the human gene encoding the previously reported mRNA. This region contains 13 exons, spread over 6550 bp of genomic sequence. The coding sequence is only weakly similar to other IkappaBs and the exons display a more complicated structure than has been found in other members of the IkappaB gene family. Moreover, the positions of intron-exon junctions are different from those found in other IkappaB genes, even within the otherwise conserved ankyrin-like repeat region, suggesting that the IkappaBR gene is not a member of this extended gene family. We report a revised mRNA and protein sequence for IkappaBR, which predicts that the protein is larger than originally described. We also report the chromosomal localisation of the human IkappaBR gene (approved gene symbol NFKBIL2) to 8q24.3 using PCR-based somatic cell hybrid panel analysis and fluorescence in situ hybridization (FISH) mapping.