Noncovalent Dimerization of Ubiquitin

摘要

Ubiquitin is a small signaling protein in cells and is highly conserved throughout the eukaryotes. Ubiquitin interacts with myriad partner proteins that contain one or more ubiquitin-binding domains (UBDs). To achieve multivalent binding with several UBDs, ubiquitins are often covalently linked by an isopeptide bond between the C-terminal carboxyl group of one ubiquitin and a primary amine in another; the two sub units in a di-ubiquitin are referred to as the proximal unit and the distal unit, respectively. All seven lysines and the N-terminus of ubiquitin can participate in the isopeptide bond. in tandem, multiple ubiquitins can be linked up to form a poly(ubiquitin).