Ankyrin Repeat Domain of I-Kappa-B

Protein Data Bank ID: 1NFI
Protein Name: Ankyrin Repeat Domain of IκBα
Organism: Escherichia coli
Title of Drawing: “Five Seals”

I know, I’m a little late. But I don’t want to miss this post as March 22. was the International Day of Seals. So here are the seals based on the IκBα protein, which, by the way, has been suggested by a guest of my blog.

IκBα belongs to the family of proteins which can inhibit the nuclear factor NF-κB. Therefore, first, it is important to understand the function of the latter protein. NF-κB is a transcription factor, meaning that it can go to the nucleus and bind DNA thereby controlling the transcription of special genes. This translocation to the nucleus requires some activating processes. In the case of NF-κB activation happens upon stress such as irradiation, free radicals, bacterial and viral intrusion, etc. This leads to a specific response helping the cell to overcome these stress conditions. In an unstressed situation NF-κB is inactive. IκBα is responsible for the inactivation of NF-κB by binding and sequestering it in the cytoplasm, thereby preventing its translocation to the nucleus. This inhibition is necessary to avoid chronic activation of NF-κB which might lead to cancer. It is the here shown ankyrin repeat domain of IκBα by which it masks the nuclear localization signals domain of NF-κB. Generally, the ankyrin repeat domain is responsible for protein-protein interactions and can be found in many different proteins.