Recombinant UBR5 (G2216-V2799)GSGSGS(ΔE2307-D2499), HECT Domain, Ubiquitin Protein E3 Ligase Component N-Recognin 5

The construct includes the catalytic HECT-domain of UBR5 spanning residues G2216-V2799. Part of the MLLE domain was deleted (ΔE2307-D2499) and replaced with a flexible linker (GSGSGS) as part of a crystallization strategy. The catalytic cysteine in the C-terminal lobe (C-lobe) as well as the E2-binding site in the N-terminal lobe ( N-lobe) are accessible for soaking of small and middle-sized compounds.

Protein Construct: UBR5(HECT)(G2216-V2799)GSGSGS(ΔE2307-D2499)
Source: Human
Expression Host: Escherichia coli
Molecular weight [kDa]: 45.1
pI: 8.39
Extinction Coefficient [M^-1cm^-1]: 36900
Concentration: 34.27 mg/mL
Storage Buffer: 20 mM HEPES pH 7.4, 200 mM NaCl, 0.5 mM TCEP, 5% glycerol
Tag: none

Amino acid sequence:

QC Data: Datasheet
Purity SDS: >95 %
Hydrodynamic Radius (nm): 3.7
Polydispersity Index (PDI): 0.1
T_on (°C): 43.9
T_m (°C): 48.1

Structure and function

The nuclear E3 Ligase UBR5 belongs to the family of HECT Ligases, which is next to RING E3 Ligases one of the two major E3 Ligase classes. HECT Ligases typically operate as single-chain enzymes, incorporating both substrate-binding and catalytic components within the same polypeptide structure. The HECT domain itself consists of a large N-lobe which recruits E2-ubiquitin complexes and a smaller C-lobe which contains the catalytic cysteine involved in ubiquitin transfer. The basis for the recognition of a wide range of substrates is given through a high degree of structural heterogeneity that enables independence from adaptor proteins. The catalytic C-terminal HECT-domain, though, is highly conserved throughout the HECT-type E3 ligases: It catalyzes the ubiquitin transfer from the ubiquitin-loaded E2 to the substrate and thus determines UBR5 activity. Interestingly, recent research indicates that UBR5 has a preference for already ubiquitinated substrates, and might act as an efficient ubiquitin chain elongator (Hodakova, 2023). UBR5 typically occurs in a dimeric state that can further oligomerize into trimers or tetramers.

UBR5 as an important drug target

UBR5 has been associated with tumor-suppressing effects as well as enhancement of tumor growth, which can be explained by the large substrate diversity of UBR5. Especially its localisation in the nucleus, makes UBR5 an interesting target in the cancer therapeutics field. One example is the suppression of UBR5 in pancreatic cancer, which has been shown to raise the chemotherapeutic sensitivity of pancreatic cancer cells to Gemcitabine - a pancreatic tumor suppressor (Du et al., 2024). Apart from that, the UBR5 drug development approach focuses on harnessing its activity to degrade oncogenic proteins like transcription factors or nuclear receptors via targeted protein degradation. Here, strategies involve enhancing the degradation of native UBR5-targets by molecular glues that improve substrate recruitment or ligands that expose the degron sequence of e.g. oncogenic transcription factors (Taherbhoy et al., 2023).