Ubiquilin-4 - Q99NB8 (UBQL4_MOUSE)


Protein Feature View of PDB entries mapped to a UniProtKB sequence  

Regulator of protein degradation that mediates the proteasomal targeting of misfolded, mislocalized or accumulated proteins (By similarity). Acts by binding polyubiquitin chains of target proteins via its UBA domain and by interacting with subunits of the proteasome via its ubiquitin-like domain (By similarity). Key regulator of DNA repair that represses homologous recombination repair: in response to DNA damage, recruited to sites of DNA damage following phosphorylation by ATM and acts by binding and removing ubiquitinated MRE11 from damaged chromatin, leading to MRE11 degradation by the proteasome (By similarity). MRE11 degradation prevents homologous recombination repair, redirecting double-strand break repair toward non-homologous end joining (NHEJ) (By similarity). Specifically recognizes and binds mislocalized transmembrane-containing proteins and targets them to proteasomal degradation (By similarity). Collaborates with DESI1/POST in the export of ubiquitinated proteins from the nucleus to the cytoplasm (By similarity). Plays a role in the regulation of the proteasomal degradation of non-ubiquitinated GJA1 (PubMed:18079109, PubMed:20940304). Acts as an adapter protein that recruits UBQLN1 to the autophagy machinery (By similarity). Mediates the association of UBQLN1 with autophagosomes and the autophagy-related protein LC3 (MAP1LC3A/B/C) and may assist in the maturation of autophagosomes to autolysosomes by mediating autophagosome-lysosome fusion (By similarity). UniProt
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Subunit Structure
Homooligomer (By similarity). Binds signal sequences of proteins that are targeted to the endoplasmic reticulum (PubMed:11162551). Interacts (via UBA domain) with GJA1 (not ubiquitinated) and with ubiquitin; both compete for the same binding site (PubMed:18079109, PubMed:20127391, PubMed:20940304). Interacts (via UBA domain) with ubiquitin and with polyubiquitin chains (PubMed:20940304). Interacts (via ubiquitin-like domain) with PSMD2 and PSMD4, regulatory subunits of the 26S proteasome (PubMed:18079109). Interacts with ATXN1/SCA1; interaction with ATXN1 inhibits polyubiquitination of UBQLN4 and interferes with PSMD4 binding (By similarity). Interacts with HERPUD1 (By similarity). Interacts (via ubiquitin-like domain) with UBQLN1 (via UBA domain) (By similarity). Interacts with UBQLN2 (By similarity). Interacts (via STI1 1 and 2 domains) with MAP1LC3A/B/C (By similarity). Interacts with BAG6 (By similarity). Interacts with MRE11 (when ubiquitinated); interaction with ubiquitinated MRE11 leads to MRE11 removal from chromatin (By similarity). Interacts with DESI1/POST; leading to nuclear export (By similarity). UniProt
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Data in green originates from UniProtKB  
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Data in yellow originates from Pfam  , by interacting with the HMMER3 web site  
Data in purple originates from Phosphosite  .
Data in orange originates from the SCOP   (version 1.75) and SCOPe   (version 2.04) classifications.
Data in grey has been calculated using BioJava  . Protein disorder predictions are based on JRONN (Troshin, P. and Barton, G. J. unpublished), a Java implementation of RONN  
  • Red: potentially disorderd region
  • Blue: probably ordered region.
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Data in lilac represent the genomic exon structure projected onto the UniProt sequence.
Data in blue originates from PDB
  • Secstruc: Secondary structure projected from representative PDB entries onto the UniProt sequence.
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Data in red indicates combined ranges of Homology Models from the SWISS-MODEL Repository  
The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).
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