Ubiquitination targets proteins for degradation by the sequential attachment of ubiquitin to lysine residues within the substrate molecule. Target specificity is determined by the E3 ubiquitin-protein ligases. One class of E3s consists of the heterotetrameric Skp1-Cullin-F box (SCF) complexes. The mammalian F-box protein β-TRCP directs the degradation of IκBα by binding to a phosphorylated decapeptide site within the IκBα molecule.
In the July 17