• Purity

  >95%, by SDS-PAGE under reducing conditions and visualized by Colloidal Coomassie? Blue stain.

• Activity

  The lysine residue utilized for Ubiquitin chain formation is functionally important. Ubiquitin lysine to arginine mutants are ideal for investigating biological processes involving a particular Ubiquitin chain linkage. Recombinant Human Ubiquitin Mutant K33R prevents the formation of K33-linked Ubiquitin chains. Reaction conditions will need to be optimized for each specific application. We recommend an initial Recombinant Human Ubiquitin Mutant K33R concentration of 50-500 μM.

• Source

  E. coli-derived

• Accession #

• Predicted Molecular Mass

  8.6 kDa

Background: Ubiquitin

Ubiquitin is a 76 amino acid (aa) protein that is ubiquitously expressed in all eukaryotic organisms. Ubiquitin is highly conserved with 96% aa sequence identity shared between human and yeast Ubiquitin, and 100% aa sequence identity shared between human and mouse Ubiquitin (1). In mammals, four Ubiquitin genes encode for two Ubiquitin-ribosomal fusion proteins and two poly-Ubiquitin proteins. Cleavage of the Ubiquitin precursors by deubiquitinating enzymes gives rise to identical Ubiquitin monomers each with a predicted molecular weight of 8.6 kDa. Conjugation of Ubiquitin to target proteins involves the formation of an isopeptide bond between the C-terminal glycine residue of Ubiquitin and a lysine residue in the target protein. This process of conjugation, referred to as ubiquitination or ubiquitylation, is a multi-step process that requires three enzymes: a Ubiquitin-activating (E1) enzyme, a Ubiquitin-conjugating (E2) enzyme, and a Ubiquitin ligase (E3). Ubiquitination is classically recognized as a mechanism to target proteins for degradation and as a result, Ubiquitin was originally named ATP-dependent Proteolysis Factor 1 (APF-1) (2,3). In addition to protein degradation, ubiquitination has been shown to mediate a variety of biological processes such as signal transduction, endocytosis, and post-endocytic sorting (4-7).

Mutation of lysine 33 to arginine renders Ubiquitin (Ub) unable to form poly-Ubiquitin chains via lysine 33 linkages with other Ubiquitin molecules. Ubiquitin K33R can form a Ubiquitin-activating (E1) enzyme-catalyzed active thioester at the C-terminus allowing the molecule to be transferred to the lysines of substrate proteins. Ideal for the reduction in poly-Ubiquitin chain length/conjugation rates and determining if poly-Ubiquitin chains are K33 linked.

• References:

1. Sharp, P.M. & W.-H. Li. (1987) Trends Ecol. Evol. 2:328.

2. Ciechanover, A. et al. (1980 ) Proc. Natl. Acad. Sci. USA 77:1365.

3. Hershko, A. et al. (1980) Proc. Natl. Acad. Sci. USA 77:1783.

4. Greene, W. et al. (2012) PLoS Pathog. 8:e1002703.

5. Tong, X. et al. (2012) J. Biol. Chem. 287:25280.

6. Wei, W. et al. (2004) Nature 428:194.

7. Wertz, I.E. et al. (2004) Nature 430:694.

• Entrez Gene IDs:

  7314 (Human); 298693 (Rat)

• Alternate Names:

  RPS27A; UBA52; UBB ubiquitin B; UBB; UBC; Ubiquitin