DDB2

This gene encodes a protein that is necessary for the repair of ultraviolet light-damaged DNA. This protein is the smaller subunit of a heterodimeric protein complex that participates in nucleotide excision repair, and this complex mediates the ubiquitylation of histones H3 and H4, which facilitates the cellular response to DNA damage. This subunit appears to be required for DNA binding. Mutations in this gene cause xeroderma pigmentosum complementation group E, a recessive disease that is characterized by an increased sensitivity to UV light and a high predisposition for skin cancer development, in some cases accompanied by neurological abnormalities. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2014]

Damage Specific DNA Binding Protein 2

Protein, which is both involved in DNA repair and protein ubiquitination, as part of the UV-DDB complex and DCX (DDB1-CUL4-X-box) complexes, respectively (PubMed:10882109, PubMed:11278856, PubMed:11705987, PubMed:9892649, PubMed:12732143, PubMed:15882621, PubMed:16473935, PubMed:18593899).

Core component of the UV-DDB complex (UV-damaged DNA-binding protein complex), a complex that recognizes UV-induced DNA damage and recruit proteins of the nucleotide excision repair pathway (the NER pathway) to initiate DNA repair (PubMed:10882109, PubMed:11278856, PubMed:11705987, PubMed:16260596, PubMed:12944386, PubMed:14751237).

The UV-DDB complex preferentially binds to cyclobutane pyrimidine dimers (CPD), 6-4 photoproducts (6-4 PP), apurinic sites and short mismatches (PubMed:10882109, PubMed:11278856, PubMed:11705987, PubMed:16260596, PubMed:12944386).

Also functions as the substrate recognition module for the DCX (DDB2-CUL4-X-box) E3 ubiquitin-protein ligase complex DDB2-CUL4-ROC1 (also known as CUL4-DDB-ROC1 and CUL4-DDB-RBX1) (PubMed:12732143, PubMed:15882621, PubMed:16473935, PubMed:18593899, PubMed:26572825).

The DDB2-CUL4-ROC1 complex may ubiquitinate histone H2A, histone H3 and histone H4 at sites of UV-induced DNA damage (PubMed:16678110, PubMed:16473935).

The ubiquitination of histones may facilitate their removal from the nucleosome and promote subsequent DNA repair (PubMed:16678110, PubMed:16473935).

The DDB2-CUL4-ROC1 complex also ubiquitinates XPC, which may enhance DNA-binding by XPC and promote NER (PubMed:15882621).

The DDB2-CUL4-ROC1 complex also ubiquitinates KAT7/HBO1 in response to DNA damage, leading to its degradation: recognizes KAT7/HBO1 following phosphorylation by ATR (PubMed:26572825).

Isoform D1:
Inhibits UV-damaged DNA repair.

Isoform D2:
Inhibits UV-damaged DNA repair.

DNA repair Source: GO_Central
Global genome nucleotide-excision repair Source: Reactome
Histone H2A monoubiquitination Source: UniProtKB
Nucleotide-excision repair Source: ProtInc
Nucleotide-excision repair, DNA damage recognition Source: Reactome
Nucleotide-excision repair, DNA duplex unwinding Source: Reactome
Nucleotide-excision repair, DNA incision Source: Reactome
Nucleotide-excision repair, DNA incision, 3'-to lesion Source: Reactome
Nucleotide-excision repair, DNA incision, 5'-to lesion Source: Reactome
Nucleotide-excision repair, preincision complex assembly Source: Reactome
Nucleotide-excision repair, preincision complex stabilization Source: Reactome
Post-translational protein modification Source: Reactome
Protein autoubiquitination Source: UniProtKB
Protein deubiquitination Source: Reactome
Protein polyubiquitination Source: UniProtKB
Pyrimidine dimer repair Source: Ensembl
Response to UV Source: UniProtKB
UV-damage excision repair Source: UniProtKB

Nucleus. Accumulates at sites of DNA damage following UV irradiation.

Xeroderma pigmentosum complementation group E (XP-E):
An autosomal recessive pigmentary skin disorder characterized by solar hypersensitivity of the skin, high predisposition for developing cancers on areas exposed to sunlight and, in some cases, neurological abnormalities. The skin develops marked freckling and other pigmentation abnormalities. XP-E patients show a mild phenotype with minimal or no neurologic features.

Phosphorylation by ABL1 negatively regulate UV-DDB activity.
Ubiquitinated by CUL4A in response to UV irradiation. Ubiquitination appears to both impair DNA-binding and promotes ubiquitin-dependent proteolysis. Degradation of DDB2 at sites of DNA damage may be a prerequisite for their recognition by XPC and subsequent repair. CUL4A-mediated degradation appears to be promoted by ABL1.
Ubiquitinated, leading to proteasomal degradation, and deubiquitinated by USP24.