Cullins are a family of hydrophobic proteins that act as scaffolds for ubiquitin ligases (E3). Cullins are found throughout eukaryotes. Humans express several cullins (Cul1, 2, 3, 4A, 4B, 5, 7 and 9), each forming part of a multi-subunit ubiquitin complex [ PUBMED:36041947 PUBMED:24793696 … expand

Cullins are a family of hydrophobic proteins that act as scaffolds for ubiquitin ligases (E3). Cullins are found throughout eukaryotes. Humans express several cullins (Cul1, 2, 3, 4A, 4B, 5, 7 and 9), each forming part of a multi-subunit ubiquitin complex [ PUBMED:36041947 PUBMED:24793696 ]. Cullin-RING ubiquitin ligases (CRLs), such as Cul1 (SCF) [ PUBMED:8681378 ], play an essential role in targeting proteins for ubiquitin-mediated destruction; as such, they are diverse in terms of composition and function, regulating many different processes from glucose sensing and DNA replication to limb patterning and circadian rhythms. The catalytic core of CRLs consists of a RING protein and a cullin family member. For Cul1, the C-terminal cullin-homology domain binds the RING protein. The RING protein appears to function as a docking site for ubiquitin-conjugating enzymes (E2s). Other proteins contain a cullin-homology domain, such as the APC2 subunit of the anaphase-promoting complex/cyclosome and the p53 cytoplasmic anchor PARC; both APC2 and PARC have ubiquitin ligase activity. The N-terminal region of cullins is more variable, and is used to interact with specific adaptor proteins [ PUBMED:15688063 PUBMED:11961546 PUBMED:15537541 ].