Summary: Cullin family
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structure of the cul1-rbx1-skp1-f boxskp2 scf ubiquitin ligase complex
|Cullin protein neddylation domain|
structure of the cul1-rbx1-skp1-f boxskp2 scf ubiquitin ligase complex
Cullins are a family of hydrophobic proteins providing a scaffold for ubiquitin ligases (E3). All eukaryotes appear to have cullins. They combine with RING proteins to form Cullin-RING ubiquitin ligases (CRLs) that are highly diverse and play a role in a myriad of cellular processes.
Human genome contains seven cullin genes:
- CUL1, part of SCF complex
- CUL2, part of ECS complex (Elongin C - CUL2 - SOCS-box)
- CUL3, part of CUL3-BTB complex
- a more distant member called ANAPC2, part of Anaphase-promoting complex
Cullin-RING ubiquitin ligases (CRLs), such as Cul1 (SCF) 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.
With the exception of APC2, each member of the cullin family is modified by Nedd8 and several cullins function in Ubiquitin-dependent proteolysis, a process in which the 26S proteasome recognises and subsequently degrades a target protein tagged with K48-linked poly-ubiquitin chains. Nedd8/Rub1 is a small ubiquitin-like protein, which was originally found to be conjugated to Cdc53, a cullin component of the SCF (Skp1-Cdc53/CUL1-F-box protein) E3 Ub ligase complex in Saccharomyces cerevisiae (Baker's yeast), and Nedd8 modification has now emerged as a regulatory pathway of fundamental importance for cell cycle control and for embryogenesis in metazoans. The only identified Nedd8 substrates are cullins. Neddylation results in covalent conjugation of a Nedd8 moiety onto a conserved cullin lysine residue.
- Kipreos ET, Lander LE, Wing JP, He WW, Hedgecock EM (June 1996). "cul-1 is required for cell cycle exit in C. elegans and identifies a novel gene family". Cell 85 (6): 829–39. doi:10.1016/S0092-8674(00)81267-2. PMID 8681378.
- Petroski MD, Deshaies RJ (January 2005). "Function and regulation of cullin-RING ubiquitin ligases". Nat. Rev. Mol. Cell Biol. 6 (1): 9–20. doi:10.1038/nrm1547. PMID 15688063.
- Zheng N, Schulman BA, Song L, Miller JJ, Jeffrey PD, Wang P, Chu C, Koepp DM, Elledge SJ, Pagano M, Conaway RC, Conaway JW, Harper JW, Pavletich NP (April 2002). "Structure of the Cul1-Rbx1-Skp1-F boxSkp2 SCF ubiquitin ligase complex". Nature 416 (6882): 703–9. doi:10.1038/416703a. PMID 11961546.
- Goldenberg SJ, Cascio TC, Shumway SD, Garbutt KC, Liu J, Xiong Y, Zheng N (November 2004). "Structure of the Cand1-Cul1-Roc1 complex reveals regulatory mechanisms for the assembly of the multisubunit cullin-dependent ubiquitin ligases". Cell 119 (4): 517–28. doi:10.1016/j.cell.2004.10.019. PMID 15537541.
- Pan ZQ, Kentsis A, Dias DC, Yamoah K, Wu K (March 2004). "Nedd8 on cullin: building an expressway to protein destruction". Oncogene 23 (11): 1985–97. doi:10.1038/sj.onc.1207414. PMID 15021886.
- Cullin family - Sanger Institute website.
- Cullin Proteins at the US National Library of Medicine Medical Subject Headings (MeSH)
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This tab holds annotation information from the InterPro database.
InterPro entry IPR001373
Cullins are a family of hydrophobic proteins that act as scaffolds for ubiquitin ligases (E3). Cullins are found throughout eukaryotes. Humans express seven cullins (Cul1, 2, 3, 4A, 4B, 5 and 7), each forming part of a multi-subunit ubiquitin complex. 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].
This entry represents the N-terminal region of cullin proteins, which consists of several domains, including cullin repeat domain, a 4-helical bundle domain, an alpha+beta domain, and a winged helix-like domain.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||cullin-RING ubiquitin ligase complex (GO:0031461)|
|Molecular function||ubiquitin protein ligase binding (GO:0031625)|
|Biological process||ubiquitin-dependent protein catabolic process (GO:0006511)|
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|Seed source:||Pfam-B_1149 (release 3.0)|
|Number in seed:||47|
|Number in full:||2251|
|Average length of the domain:||484.10 aa|
|Average identity of full alignment:||20 %|
|Average coverage of the sequence by the domain:||65.66 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||17|
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There are 5 interactions for this family. More...
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Cullin domain has been found. There are 30 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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