Ubiquitin K→R Mutant Proteins Set

Background: The Ubiquitin K→R Mutant Proteins Set is a set of mutant ubiquitin proteins in which each of the seven lysine residues in Ubiquitin (K6, K11, K27, K29, K33, K48, and K63) have been individually mutated to arginine, along with a lysine-null ubiquitin variant in which all lysines are substituted (Ubiquitin, NoK). These mutants selectively prevent ubiquitin chain elongation through specific lysine residues, allowing for interrogation of individual linkage sites in ubiquitin chain formation. By removing individual lysine acceptor sites, this panel enables determination of which linkages are utilized by specific E2/E3 enzyme pairs during ubiquitylation reactions. The Ubiquitin, NoK variant serves as an important control to restrict ubiquitylation to mono-ubiquitylation events or to assess ubiquitin transfer independent of polyubiquitin chain assembly. This kit supports mechanistic studies of ubiquitin ligases, mapping of ubiquitin chain architecture, and characterization of linkage-specific ubiquitylation pathways. These reagents are well suited for in vitro ubiquitylation assays, enzyme profiling, and screening workflows targeting the Ubiquitin Proteasome System.