K48-linked Tetra-Ubiquitin (human) (rec.) (untagged)

Recombinant Protein. Four enzymatically conjugated human ubiquitin (aa1-76) covalently linked through an isopeptide bond at K48 residue of one ubiquitin molecule and the C-terminal glycine residue of another ubiquitin molecule and untagged. Source/Host: E. coli. Liquid. In 50mM HEPES pH 7.5. The array of cellular processes initiated and regulated by ubiquitin has been partially explained by the structural diversity of differently linked ubiquitin chains. In a ubiquitin chain, ubiquitin moieties can be conjugated through one of their lysine residues (K6, K11, K27, K29, K33, K48 and K63) or the N-terminal methionine residue (M1), offering countless possibilities to assemble a specific polymer. Ubiquitin molecules can also be modified by other post-translational modifications, including acetylation and phosphorylation, adding another layer of ubiquitin signal regulation and diversification. K48-polyubiquitin chains are the most abundant linkage in cells and thought to be the major signal for proteasome-mediated degradation. Quantitative MS analyses of intracellular ubiquitin linkages reveled K48-polyubiquitin linkages rapidly accumulate when cells are treated with the proteasome inhibitor MG132. This protein is formed with wild-type human recombinant ubiquitin and linkage-specific enzymes. Ideal for investigating ubiquitin-binding proteins and as substrates for ubiquitin-specific isopeptidases. Reaction conditions will need to be optimized for each specific application.