Cloning and characterization of the gene encoding mouse IκBβ

I kappa B beta is a member of the I kappa B family of structurally related proteins that are important regulators of the inducible transcription factor NF-kappa B. In the present study, the mouse I kappa B beta gene was cloned and sequenced, and its structure determined. The mouse I kappa B beta gene contains six exons and five introns that span 7435 nucleotides. A single major transcription initiation site is located 59 nucleotides upstream of the initiating methionine. A translation termination codon and a single polyadenylation signal are found within exon 6. The exon/intron structure of I kappa B beta and I kappa B alpha genes were compared and found to be very similar, with individual ankyrin repeats being maintained on corresponding exons. This suggests a close evolutionary relationship between these two I kappa B isoforms. The significance of this evolutionary relationship is discussed. (C) 2000 Published by Elsevier Science B.V. All rights reserved.