CUL4B - Cullin-4B - human protein (Function)
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CUL4B »  Cullin-4B  (CUL-4B)
Gene name:  CUL4B
Family name: Cullin
Entry whose protein(s) existence is based on evidence at protein level
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Core component of multiple cullin-RING-based E3 ubiquitin-protein ligase complexes which mediate the ubiquitination and subsequent proteasomal degradation of target proteins. The functional specificity of the E3 ubiquitin-protein ligase complex depends on the variable substrate recognition subunit. CUL4B may act within the complex as a scaffold protein, contributing to catalysis through positioning of the substrate and the ubiquitin-conjugating enzyme. Plays a role as part of the E3 ubiquitin-protein ligase complex in polyubiquitination of CDT1, histone H2A, histone H3 and histone H4 in response to radiation-induced DNA damage. Targeted to UV damaged chromatin by DDB2 and may be important for DNA repair and DNA replication. Required for ubiquitination of cyclin E, and consequently, normal G1 cell cycle progression. Regulates the mammalian target-of-rapamycin (mTOR) pathway involved in control of cell growth, size and metabolism. Specific CUL4B regulation of the mTORC1-mediated pathway is dependent upon 26S proteasome function and requires interaction between CUL4B and MLST8.  
  • CuratedUniProtKB
GO molecular function 
Protein bindingdefinition[GO:0005515]  
  • IPIIntAct
Ubiquitin protein ligase bindingdefinition[GO:0031625] silver  
  • IEAInterPro 2 GO
GO biological process 
Cell cycledefinition[GO:0007049]  
  • NASUniProtKB
DNA repairdefinition[GO:0006281]  
  • IEAUniProtKB KW
Positive regulation of G1/S transition of mitotic cell cycledefinition[GO:1900087] silver  
  • IEAOrtholog Compara
Positive regulation of protein catabolic processdefinition[GO:0045732] silver  
  • IEAOrtholog Compara
Protein ubiquitinationdefinition[GO:0016567]  
  • IEAUniPathway
Ubiquitin-dependent protein catabolic processdefinition[GO:0006511] silver  
  • IEAInterPro 2 GO
This protein is involved in the following pathway
According to KEGG, this protein belongs to the following pathways:
Nucleotide excision repair  hsa03420+8450  
Ubiquitin mediated proteolysis  hsa04120+8450  


Biological process 
Cell cycle  definition   [KW-0131]
DNA damage  definition   [KW-0227]
DNA repair  definition   [KW-0234]
Ubl conjugation pathway  definition   [KW-0833]
Technical term 
Reference proteome  definition   [KW-1185]

Further external links

GeneWiki: CUL4B
GenomeRNAi: 8450
PRO: PR:Q13620