Function
NFE2, NFE2L1, and NFE2L2 (this protein) comprise a family of human genes encoding basic leucine zipper (bZIP) transcription factors. They share highly conserved regions that are distinct from other bZIP families, such as JUN and FOS, although remaining regions have diverged considerably from each other.
Under normal or unstressed conditions, Nrf2 is kept in the cytoplasm by a cluster of proteins that degrade it quickly. Under oxidative stress, Nrf2 is not degraded, but instead travels to the nucleus where it binds to a DNA promoter and initiates transcription of antioxidative genes and their proteins.
Nrf2 is kept in the cytoplasm by Kelch like-ECH-associated protein 1 (Keap1) and Cullin 3 which degrade Nrf2 by ubiquitination. Cullin 3 ubiquitinates its substrate, Nrf2. Keap1 is a substrate adaptor, which helps Cullin 3 ubiquitinate Nrf2. When Nrf2 is ubiquitinated, it is transported to the proteasome, where it is degraded and its components recycled. Under normal conditions Nrf2 has a half-life of only 20 minutes. Oxidative stress or electrophilic stress disrupts critical cysteine residues in Keap1, disrupting the Keap1-Cul3 ubiquitination system. When Nrf2 is not ubiquitinated, it builds up in the cytoplasm, and translocates into the nucleus. In the nucleus, it combines (forms a heterodimer) with a small Maf protein and binds to the Antioxidant Response Element (ARE) in the upstream promoter region of many antioxidative genes, and initiates their transcription.
Read more about this topic: NFE2L2
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