Recombinant Human K33-linked Di-Ubiquitin

Background: K33-linked ubiquitin chains are formed when the C-terminal glycine 76 of one ubiquitin is conjugated to lysine 33 of another, generating homotypic or branched polyubiquitin assemblies. They adopt a relatively compact conformation that supports selective recognition by ubiquitin-binding domains such as those found in trafficking and signaling adaptors. K33 linkages are assembled by E3 ligases including Cbl-b and members of the NEDD4 family in conjunction with specific E2 enzymes. Functionally, K33-linked ubiquitination regulates membrane protein trafficking, T cell receptor signaling, and kinase modification without directly targeting substrates for proteasomal degradation. Deubiquitylases such as TRABID exhibit activity toward K29 and K33 linkages, contributing to the control of signaling pathways and protein turnover.