FBXL5

The hemerythrin-like region acts as an oxygen and iron sensor by binding oxygen through a diiron metal-center. In absence of oxygen and iron, the protein is ubiquitinated and degraded.

Component of some SCF (SKP1-cullin-F-box) protein ligase complex that plays a central role in iron homeostasis by promoting the ubiquitination and subsequent degradation of IREB2/IRP2 (PubMed:19762596, PubMed:19762597). The C-terminal domain of FBXL5 contains a redox-sensitive [2Fe-2S] cluster that, upon oxidation, promotes binding to IRP2 to effect its oxygen-dependent degradation (PubMed:32126207). Under iron deficiency conditions, the N-terminal hemerythrin-like (Hr) region, which contains a diiron metal center, cannot bind iron and undergoes conformational changes that destabilize the FBXL5 protein and cause its ubiquitination and degradation (PubMed:19762596, PubMed:19762597). When intracellular iron levels start rising, the Hr region is stabilized (PubMed:19762596, PubMed:19762597). Additional increases in iron levels facilitate the assembly and incorporation of a redox active [2Fe-2S] cluster in the C-terminal domain (PubMed:32126207). Only when oxygen level is high enough to maintain the cluster in its oxidized state can FBXL5 recruit IRP2 as a substrate for polyubiquination and degradation (PubMed:32126207). Promotes ubiquitination and subsequent degradation of the dynactin complex component DCTN1 (PubMed:17532294). Within the nucleus, promotes the ubiquitination of SNAI1; preventing its interaction with DNA and promoting its degradation (PubMed:24157836). Negatively regulates DNA damage response by mediating the ubiquitin-proteasome degradation of the DNA repair protein NABP2 (PubMed:25249620).

Protein modification; protein ubiquitination.

Polybiquitinated upon iron and oxygen depletion, leading to its degradation by the proteasome. Ubiquitination is regulated by the hemerythrin-like region that acts as an oxygen and iron sensor. Undergoes constitutive ubiquitin-dependent degradation at the steady state by HERC2 (PubMed:24778179).

• Cytoplasm
• Perinuclear region
• Nucleus

FBL4, FBL5, FLR1, FBXL5, F-box/LRR-repeat protein 5, F-box and leucine-rich repeat protein 5, F-box protein FBL4/FBL5, p45SKP2-like protein

• entrezGene:26234
• omim:605655
• swissprot:Q9UKA1

Proteins

Oncology

78555Da