| Modification Notes |
In eukaryotes, degradation of damaged or excess proteins into short peptides is carried out by proteasomes. The proteasomes bind polyubiquitin chains that are added to the target proteins through a phosphorylation-dependent reaction catalyzed by ubiquitin ligases, such as the SCF-type E3 complex containing Skp, Cullin, Rbx1 and F-box proteins. F-box proteins, such as FBXO6 (F-box only protein 6), possess structural motifs used for directly aggregating the substrate while binding to the Skp1 bridge providing for close proximity to the functional E2 ubiquitin-conjugating enzyme, Cullin/Rbx1. FBXO6, also known as FBG2 or FBX6, is a 293 amino acid protein that contains a 40 amino acid binding motif. Human FBXO6 shows significant sequence identity to rat NFB42, a protein related to cell cycle control. High expression of FBXO6 is known in brain, skeletal muscle, spleen, liver and testis. |
