ddb1 complex update

[Antonialock]

might be part of Cul4B-RING E3 ubiquitin ligase complex, COP9 signalosome

[ValWood]

why do you think this?

[Antonialock]

looks like it links the complex to substrates

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2783741/pdf/nihms143786.pdf

[Antonialock]

Rik1, Cul4, Pip1, and Dos1 show strong resemblance to subunits of Cullin-RING ubiquitin ligases (CRLs), the largest family of multisubunit E3 ubiquitin ligases (13). CLRC is most similar to the human CRL4 complex, which contains the cullin CUL4 that serves as a scaffold to bring the E2-ubiquitin–conjugating enzyme in proximity to its substrate (14). In CRL4, the RING finger subunit RBX1/2, bound to the C terminus of CUL4, recognizes the E2 enzyme, whereas an adaptor subunit, the DNA damage binding protein 1 (DDB1), bound to the CUL4 N terminus, recruits a variety of WD-40 substrate receptors, known as DCAFs (DDB1 CUL4 associated factors) that recognize specific substrates (15–18). The best characterized DCAF, DDB2, acts as a DNA damage sensor, binding pyrimidine dimers at UV lesions, and as part of the RBX1/CUL4/DDB1/DDB2 complex (CRL4DDB2), ubiquitylates histones and DNA repair proteins (19). The structure of CRL4DDB2 displays a U-shaped architecture, with the DCAF DDB2 recognizing damaged DNA through its β-propeller while bound to the adapter DDB1 (19). By analogy, it has been proposed that Rik1 assumes the function of DDB1 and that Dos1 is the DCAF involved in target recognition in the CLRC complex (20, 21). Biochemical and genetic data show that CLRC is an active ubiquitin ligase and that the ligase activity is required for heterochromatin formation (7, 8). However, functional bona fide targets of CLRC remain unknown.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3918804/

[Antonialock]

so CLRC complex needs rbx1 (GO:0043494 - CLRC ubiquitin ligase complex) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3918804/

[Antonialock]

and GO:0080008 Cul4-RING E3 ubiquitin ligase complex ddb1, pcu4, rbx1

TAS PMID:27098497

The Cullin 4 ring E3 ubiquitin ligases (CRL4s) regulate a wide variety of biological processes including chromatin remodelling, DNA replication and repair9. Like SCF (Skp1-CUL1-F box) complexes, CRL4s consist of a core set of components (CUL4-DDB1-ROC) associated with one of a variety of substrate-specific adaptors that target defined proteins to CRL4 for ubiquitin-dependent modification. These adaptors form a family of ‘DWD' (DDB1-binding WD40) proteins that define multiple CRL4 complexes (that is, CRL4Cdt2; CRL4Ddb2; and so on)9. Database search and biochemical analysis predict that about one-third of the human WD40 proteins contain DWD motif and thus are prospective CRL4 targeting subunits. Only few of these have been biologically characterized.

[Antonialock]

done updates also updated ddb1 product