Activity: Fully hydrolyzed by the K63-specific AMSH* deubiquitylase
Verified Applications: Poly-ubiquitin chains exhibit diversity in length, linkage type, and associated cellular functions. K63-linked tetra-ubiquitin serves as a valuable reagent in assays involving ubiquitin-binding proteins and as a substrate for ubiquitin-specific deubiquitylating enzymes (DUBs). Optimal enzyme concentrations should be empirically determined based on the specific assay context. Note: Exposure of this product to elevated temperatures in SDS-PAGE sample buffer may lead to anomalous high-molecular-weight smearing during electrophoresis, which does not reflect its actual purity. For improved resolution, we recommend pre-incubation in SDS-PAGE buffer at temperatures below 60 °C for 20 minutes prior to gel loading.
2 μg UBA1 run on 4-12% SDS-PAGE gel under reducing conditions, then visualized with Colloidal Coomassie Blue Stain.
Formulation: 10 mM HEPES, pH 7.6
Shipping: The product is shipped with dry ice or equivalent. Upon receipt, store it immediately at the temperature recommended below.
Storage and Stability: Use a manual defrost freezer and avoid repeated freeze-thaw cycles. Aliquot and store ≤ -20°C (stable for 24 months from date of receipt).
Protein Sequence: MQIFVKTLTGKTITLEVEPSDTIENVKAKIQDKEGIPPDQQRLIFAGKQLEDGRTLSDYNIQKESTLHLVLRLRGG
Background Information and Alternate Names
Species & architecture
Four 76-aa ubiquitin units connected sequentially via Lys63 isopeptide linkages. X-ray structures at 2.1 Å (PDB 3AUP) and 2.4 Å (PDB 3DVG) capture an elongated, quasi-helical chain whose inter-subunit angles propagate a continuous recognition surface. SAXS/NMR ensembles show pH- and salt-dependent “breathing” that modulates receptor affinity.
UPS pathway role
Unlike Lys48 chains, Lys63 poly-ubiquitin does not target substrates to the proteasome. Instead, it nucleates scaffold complexes in NF-κB (TRAF6→NEMO), DNA-damage tolerance (Rad5-PCNA), receptor endocytosis and innate-immune RIG-I signaling. Its exposed Lys63 residue also primes elongation into longer Lys63 polymers by Ubc13–Uev1A and related E2/E3 pairs.
Relevance to TPD & disease biology
Lys63 signaling governs inflammation, DNA-repair fidelity and oncogenic survival pathways; dysregulation contributes to autoimmune disease and cancer progression.
References
Varadan, R., et al., (2004) J Biol Chem 279:7055-63. PMID 14645257
Weeks, S. D., et al., (2009) Proteins 77:753-59. PMID
Yoshikawa, A., et al., (2009) FEBS Lett 583:3317-22. PMID 19766637
Liu, Z., et al., (2015) eLife 4:e05767. PMID 26090905
Cao, L., et al., (2022) Cell Death Discov 8:410. PMID 36202787
Alternate Names: Human Lys63-linked tetra-ubiquitin (K63-Ub₄, Ub₄-K63)
