I-kappa B, also written as IκB, is a protein that plays a crucial role in regulating the activity of nuclear factor kappa B (NF-κB), a transcription factor involved in various cellular processes such as inflammation, immune response, and cell proliferation.
In the dictionary sense, I-kappa B can be defined as a family of inhibitory proteins that bind to NF-κB and prevent its translocation to the nucleus, thereby inhibiting its ability to activate gene expression. These proteins act as inhibitors by physically blocking the DNA-binding domain of NF-κB, preventing its interaction with target genes.
The I-kappa B family consists of multiple isoforms, including IκBα, IκBβ, and IκBε, each with specific functions and tissue distribution. These proteins are characterized by ankyrin repeats, which are protein domains involved in protein-protein interactions. I-kappa B proteins are primarily present in the cytoplasm and serve as a regulatory mechanism to control the activity of NF-κB in response to different stimuli.
The degradation of I-kappa B is a critical step in the activation of NF-κB signaling pathways. Upon stimulation, such as by pro-inflammatory cytokines or pathogen invasion, I-kappa B undergoes phosphorylation by the I-kappa B kinase (IKK) complex. This phosphorylation marks I-kappa B for ubiquitination and subsequent degradation by proteasomes, leading to the release of NF-κB, allowing its translocation to the nucleus where it can induce the expression of target genes.
In summary, I-kappa B refers to a family of inhibitory proteins that regulate the activity of NF-κB by preventing its translocation into the nucleus, thereby playing a crucial
