UBE4B
Domain
The U-box domain is required for the ubiquitin protein ligase activity.
Function
Ubiquitin-protein ligase that probably functions as an E3 ligase in conjunction with specific E1 and E2 ligases (By similarity). May also function as an E4 ligase mediating the assembly of polyubiquitin chains on substrates ubiquitinated by another E3 ubiquitin ligase (By similarity). May regulate myosin assembly in striated muscles together with STUB1 and VCP/p97 by targeting myosin chaperone UNC45B for proteasomal degradation (PubMed:17369820).
Pathway
Protein modification; protein ubiquitination.
Post-translational modifications
Proteolytically cleaved by caspases during apoptosis. Cleaved efficiently at Asp-123 by caspase-6 and granzyme B. Cleaved with approximately 10-fold less efficiency at Asp-109 by caspase-3 and caspase-7.
Sequence Similarities
Belongs to the ubiquitin conjugation factor E4 family.
Tissue Specificity
Expressed in differentiated myotubes (at protein level) (PubMed:17369820). Highest expression in ovary, testis, heart and skeletal muscle (PubMed:11802788). Expression is low in colon, thymus and peripheral blood leukocytes (PubMed:11802788). Almost undetectable in lung and spleen (PubMed:11802788).
Cellular localization
- Cytoplasm
- Nucleus
Alternative names
HDNB1, KIAA0684, UFD2, UBE4B, Ubiquitin conjugation factor E4 B, Homozygously deleted in neuroblastoma 1, RING-type E3 ubiquitin transferase E4 B, Ubiquitin fusion degradation protein 2