CUL4A
Core component of multiple cullin-RING-based E3 ubiquitin-protein ligase complexes which mediate the ubiquitination and subsequent proteasomal degradation of target proteins. As a scaffold protein may contribute to catalysis through positioning of the substrate and the ubiquitin-conjugating enzyme. The E3 ubiquitin-protein ligase activity of the complex is dependent on the neddylation of the cullin subunit and is inhibited by the association of the deneddylated cullin subunit with TIP120A/CAND1. The functional specificity of the E3 ubiquitin-protein ligase complex depends on the variable substrate recognition component. DCX(DET1-COP1) directs ubiquitination of JUN. DCX(DDB2) directs ubiquitination of XPC. In association with RBX1, DDB1 and DDB2 is required for histone H3 and histone H4 ubiquitination in response to ultraviolet and may be important for subsequent DNA repair. DCX(DTL) plays a role in PCNA-dependent polyubiquitination of CDT1 and MDM2-dependent ubiquitination of TP53 in response to radiation-induced DNA damage and during DNA replication. In association with DDB1 and SKP2 probably is involved in ubiquitination of p27Kip1/p27kip. Is involved in ubiquitination of HOXA9. Component of multiple DCX (DDB1-CUL4-X-box) E3 ubiquitin- protein ligase complexes that seem to consist of DDB1, CUL4A or CUL4B, RBX1 and a variable substrate recognition component which seems to belong to a protein family described as DCAF (Ddb1- and Cul4-associated factor) or CDW (CUL4-DDB1-associated WD40-repeat) proteins. Component of the CSA complex (DCX(ERCC8) complex) containing ERCC8, RBX1, DDB1 and CUL4A; the CSA complex interacts with RNA polymerase II; upon UV irradiation it interacts with the COP9 signalosome and preferentially with the hyperphosphorylated form of RNA polymerase II. Component of the DCX(DET1-COP1) complex with the substrate recognition component DET1 and COP1. Component of the DCX(DDB2) complex with the substrate recognition component DDB2. Component of the DCX(DTL) complex with the putative substrate recognition component DTL. Interacts with DDB1, RBX1, RNF7, CTD1, TIP120A/CAND1, SKP2, p27Kip1, MDM2, TP53 and HOXA9. Interacts with DDB2; the interactions with DDB2 and CAND1 are mutually exclusive. Interacts with VPRBP, DTL, DDA1, DCAF6, DCAF4, DCAF16, DCAF17, DET1, WDTC1, DCAF5, DCAF11, WDR24A, RFWD2, PAFAH1B1, ERCC8, GRWD1, FBXW5, RBBP7, GNB2, WSB1, WSB2, NUP43, PWP1, FBXW8, ATG16L1, KATNB1, RBBP4, RBBP5 and DCAF8. May interact with WDR26, WDR51B, SNRNP40, WDR61, WDR76, WDR5. Can self- associate. Interacts with Epstein-Barr virus BPLF1. Belongs to the cullin family. 2 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.
Protein type: Ubiquitin conjugating system
Molecular Function: protein binding; ubiquitin protein ligase binding
Biological Process: ubiquitin-dependent protein catabolic process; negative regulation of cell proliferation; positive regulation of S phase of mitotic cell cycle; virus-host interaction; regulation of protein metabolic process; protein ubiquitination; cell cycle arrest; DNA repair; G1/S transition of mitotic cell cycle
SS: The number of records in which this modification site was determined using site-specific methods. SS methods include amino acid sequencing, site-directed mutagenesis, modification site-specific antibodies, specific MS strategies, etc.
