For production of poly-ubiquitin chains via K63 only. Recombinant untagged protein
K63-only ubiquitin contains only a single lysine at position 63, with all other lysines mutated to arginine. This mutation renders ubiquitin able to form multi-ubiquitin chains only via K63, while preserving the ability to form an active thioester at the C-terminus and, therefore, the ability of K63-only ubiquitin to be transferred to the lysines of substrate proteins.
