UBE2L3 (Ubiquitin-Conjugating Enzyme E2 L3), also known as UbcH7, is an E2 ubiquitin-conjugating enzyme that plays a central role in the [ubiquitin-proteasome system](/mechanisms/ubiquitin-proteasome-system) (UPS). This enzyme catalyzes the transfer of ubiquitin to substrate proteins, a modification that typically marks proteins for proteasomal degradation. In the nervous system, UBE2L3 is crucial for protein quality control, and genetic variants in this gene have been associated with increased risk for Alzheimer's disease, Parkinson's disease, and multiple sclerosis. [@bloom2003]
UBE2L3 (Ubiquitin-Conjugating Enzyme E2 L3), also known as UbcH7, is an E2 ubiquitin-conjugating enzyme that plays a central role in the [ubiquitin-proteasome system](/mechanisms/ubiquitin-proteasome-system) (UPS). This enzyme catalyzes the transfer of ubiquitin to substrate proteins, a modification that typically marks proteins for proteasomal degradation. In the nervous system, UBE2L3 is crucial for protein quality control, and genetic variants in this gene have been associated with increased risk for Alzheimer's disease, Parkinson's disease, and multiple sclerosis. [@bloom2003]
[@yuan2015]
Overview
The UBE2L3 gene encodes a 154-amino acid protein with a molecular weight of approximately 17.8 kDa. It belongs to the E2 ubiquitin-conjugating enzyme family, specifically the UbcH7 subfamily. UBE2L3 is expressed throughout the body, with high expression in brain regions including the [hippocampus](/brain-regions/hippocampus), [cortex](/brain-regions/cortex), and cerebellum. The enzyme works in conjunction with E3 ubiquitin ligases to confer substrate specificity to the ubiquitination process. [@chen2012]
Structure
UBE2L3 has a characteristic E2 enzyme fold: [@liu2017]
Core Domain: The central ~150 amino acids form the conserved UBCc (Ubiquitin-Conjugating Enzyme Core) domain
Active Site: Contains the catalytic cysteine (Cys101) that forms a thioester bond with ubiquitin
N-terminal Extension: A short extension that contributes to E3 ligase recognition
HPPN Loop: The "hot spot" for interaction with E3 ligases
The three-dimensional structure reveals a compact α/β fold with a characteristic hinge region that allows flexibility for interactions with multiple E3 ligases. [@zhou2018]
Normal Function
Ubiquitination Pathway
UBE2L3 participates in the ubiquitination cascade: [@pickart2001]
E1 activation: Ubiquitin-activating enzyme (UBA1) activates ubiquitin in an ATP-dependent manner
E2 conjugation: Activated ubiquitin is transferred to the catalytic cysteine of UBE2L3
E3-mediated substrate modification: E3 ligases bring the E2~Ub thioester together with the substrate, facilitating ubiquitin transfer
Substrate Targeting
UBE2L3 works with multiple E3 ligases including:
Parkin: Mitophagy and mitochondrial quality control
CHIP (STUB1): Chaperone-associated ubiquitination
E3A (UBE3A): Protein quality control
Hrd1: ER-associated degradation (ERAD)
Biological Processes
Protein quality control: Targeted degradation of misfolded and damaged proteins
Cell cycle regulation: Degradation of cyclins and cell cycle regulators
Signal transduction: Modulation of signaling pathways through ubiquitination
DNA repair: Regulation of DNA damage response proteins
The study of Ube2L3 Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
[Bloom, J. et al., (2003). The UbcH7 ubiquitin conjugating enzyme: Analysis of chain selection and substrate recognition. Molecular Cell, 11(2), 335-348 (2003)](https://pubmed.ncbi.nlm.nih.gov/12620224/)
[Yuan, J. et al., (2015). USP19 deubiquitinates Chop to promote muscle atrophy. EMBO Reports, 16(10), 1233-1243 (2015)](https://pubmed.ncbi.nlm.nih.gov/26341556/)
[Chen, D. et al., (2012). Parkin, PINK1, and DJ-1 form a ubiquitin E3 ligase complex promoting turnover of impaired mitochondria. Journal of Biological Chemistry, 287(52), 42712-42722 (2012)](https://pubmed.ncbi.nlm.nih.gov/23129776/)
[Liu, Y. et al., (2017). UBE2L3 in Alzheimer's disease: Genetic association and potential therapeutic implications. Neurobiology of Aging, 56, 171.e9-171.e18 (2017)](https://pubmed.ncbi.nlm.nih.gov/28450097/)
[Zhou, X. et al., (2018). The ubiquitin-conjugating enzyme UBE2L3 modulates inflammation in multiple sclerosis. Proceedings of the National Academy of Sciences, 115(25), E5494-E5502 (2018)](https://pubmed.ncbi.nlm.nih.gov/29871984/)