Related Experiment Video
Updated: Jun 9, 2026

In Vitro Analysis of E3 Ubiquitin Ligase Function
Published on: May 14, 2021
A new crystal form of Lys48-linked diubiquitin
Jean François Trempe1, Nicholas R Brown, Martin E M Noble
1Department of Biochemistry, McGill University, 3649 Promenade Sir William Osler, Montreal, Québec H3G 0B1, Canada. jean.trempe@mail.mcgill.ca
Abstract:
Lys48-linked polyubiquitin chains are recognized by the proteasome as a tag for the degradation of the attached substrates. Here, a new crystal form of Lys48-linked diubiquitin (Ub2) was obtained and the crystal structure was refined to 1.6 A resolution. The structure reveals an ordered isopeptide bond in a trans configuration. All three molecules in the asymmetric unit were in the same closed conformation, in which the hydrophobic patches of both the distal and the proximal moieties interact with each other. Despite the different crystallization conditions and different crystal packing, the new crystal structure of Ub2 is similar to the previously published structure of diubiquitin, but differences are observed in the conformation of the flexible isopeptide linkage.
More Related Videos
Related Concept Videos
Protein Complexes with Interchangeable Parts
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
Covalently Linked Protein Regulators
These groups modify specific amino acids in a protein.
The Proteasome
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. This involves participation of a series of enzymes including— E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin...
The Proteasome Structure
The proteasome is an...
Regulated Protein Degradation
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
Intralumenal Vesicles and Multivesicular Bodies

