Description
Cullin-based E3 ligases, such as SCF (Skp1-Cdc53-F-box protein), are a large family of multi-subunit ubiquitin ligases with diverse cellular functions, including the regulation of the cell cycle, of the DNA damage response, and of various transcription factors. These ligases are composed of one of six mammalian cullin homologs (Cul1, Cul2, Cul3, Cul4a, Cul4b, and Cul5), the Ring finger containing protein Rbx1/Roc1, and cullin homolog-specific adaptor and substrate recognition subunits. Activation of cullin-based ligases require the covalent modification of a conserved lysine residue in the cullin protein with the ubiquitin-like protein NEDD8. This modification is catalyzed by the Rbx1 subunit