UBE2G2 (Ubc7) [6His-tagged]

Ubiquigent

Catalog No: UBI-62-0077-020

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Species Reactivity: Human  
Source: E. coli expression  
Formula: 50 mM HEPES pH 7.5, 150 mM sodium chloride, 2 mM dithiothreitol, 10% glycerol  
Concentration: 1 mg/ml  
Molecular Weight: ~22 kDa  
Protein Sequence: Accession number: NP_003334. For full protein sequence information download the Certificate of Analysis pdf.  
Quality Control Protein Identification: Confirmed by mass spectrometry.  
Quality Control Activity: E2-Ubiquitin Thioester Loading Assay: The activity of His-UBE2G2 was validated by loading E1 UBE1 activated ubiquitin onto the active cysteine of the His-UBE2G2 E2 enzyme via a transthiolation reaction. Incubation of the UBE1 and His-UBE2G2 enzymes in the presence of ubiquitin and ATP at 30 °C was compared at two time points, T0 and T10 minutes. Sensitivity of the ubiquitin/His-UBE2G2 thioester bond to the reducing agent DTT was confirmed.   

Background

The enzymes of the ubiquitylation pathway play a pivotal role in a number of cellular processes including regulated and targeted proteasomal degradation of substrate proteins. Three classes of enzymes are involved in the process of ubiquitylation; activating enzymes (E1s), conjugating enzymes (E2s) and protein ligases (E3s). UBE2G2 is a member of the E2 conjugating enzyme family and cloning of the human gene was first described by Katsanis and Fischer (1998). The UBE2G2 gene is 2.9-kb and encodes a 165-amino-acid protein that shares 57% sequence identity with UBE2G1.  UBE2G2 is involved in protein degradation, including a process known as Endoplasmic Reticulum-Associated Degradation (ERAD). Binding of UBE2G2 to the E3 ligase GP78 via the G2BR domain significantly increases the affinity of UBE2G2 for GP78. The UBE2G2/GP78 interaction results in the preassembly of Lys-48-linked ubiquitin chains on the catalytic cysteine of UBE2G2. Growth of the polyubiquitin chain is mediated by an aminolysis-based transfer reaction between two UBE2G2 proteins; a mechanism for transferring preassembled ubiquitin chains from UBE2G2 to the lysine residue in a substrate (Das et al., 2009; Li et al., 2007). The E3 ligase HRD1 interacts with UBE2G2 to form Lys-48-linked- polyubiquitin chains on the substrate 3-Hydroxy-3-MethylGlutaryl-coenzyme A Reductase (HMGR) targeting it for degradation (Kikkert et al., 2004). A C4HC3 RING finger-containing ubiquitin ligase of the endoplasmic reticulum – TEB4 – catalyses Lys-48-linked polyubiquitylation employing UBE2G2 in vitro (Hassink et al., 2005).

References:

Das R, Mariano J, Tsai YC, Kalathur RC, Kostova Z, Li J, Tarasov SG, McFeeters RL, Altieri AS, Ji X, Byrd RA, Weissman AM. (2009) Allosteric activation of E2-RING finger-mediated ubiquitylation by a structurally defined specific E2-binding region of gp78. Mol Cell 34, 674-85.

Hassink G, Kikkert M, Voorden SV, Lee SJ, Spaapen R, Laar TV, Coleman CS, Bartee E, Fruh K, Chau V, Wiertz V. (2005) TEB4 is a C4HC3 RING finger-containing ubiquitin ligase of the endoplasmic reticulum. Biochem J 388, 647-55.

Katsanis N, Fisher EM (1998) Identification, expression, and chromosomal localization of ubiquitin conjugating enzyme 7 (UBE2G2), a human homologue of the Saccharomyces cerevisiae ubc7 gene. Genomics 51, 128-31.

Kikkert M, Doolman R, Dai M, Avner R, Hassink G, Voorden SV, Thanedar S, Roitelman J, Chau V, Wiertz E. (2004) Human HRD1 is an E3 ubiquitin ligase involved in degradation of proteins from the endoplasmic reticulum. J Biol Chem 279, 3525-34.

Li W, Tu D, Brunger AT, Ye Y (2007) A ubiquitin ligase transfers preformed polyubiquitin chains from a conjugating enzyme to a substrate. Nature 446, 333-7.