Weak protein interactions between ubiquitin and the ubiquitin-proteasome system (UPS) enzymes that mediate its covalent attachment to substrates serve to position ubiquitin for optimal catalytic transfer. We show that a small-molecule inhibitor of the E2 ubiquitin-conjugating enzyme Cdc34A, called CC0651, acts by trapping a weak interaction between ubiquitin and the E2 donor ubiquitin-binding s...

Ubiquitin-binding domains (UBDs) differentially recognize ubiquitin (ub) modifications. Some of them specifically bind mono-ub, as has been shown for the CUE domain. Interestingly, so far no significant ubiquitin binding has been observed for the CUE domain of yeast Cue1p. Cue1p is receptor and activator of the ubiquitin-conjugating enzyme Ubc7p. It integrates Ubc7p into endoplasmic reticulum (...

The involvement of red blood cell spectrin in the ubiquitination process was studied. Spectrin was found to form two ubiquitin-associated derivatives, a DTT-sensitive ubiquitin adduct and a DTT-insensitive conjugate, characteristic intermediate and final products of the ubiquitination reaction cascade. In addition to spectrin and ubiquitin, ubiquitin-activating enzyme (E1) and ATP were necessar...

Ubiquitin plays an essential role in modulating protein functions, and deregulation of the ubiquitin system leads to the development of multiple human diseases. Owing to its molecular features, ubiquitin can form various homo- and heterotypic polymers on substrate proteins, thereby provoking distinct cellular responses. The concept of multifaceted ubiquitin chains encoding different functions h...

Ubiquitination plays a central role in the regulation of various biological functions including immune responses. Ubiquitination is induced by a cascade of enzymatic reactions by E1 ubiquitin activating enzyme, E2 ubiquitin conjugating enzyme, and E3 ubiquitin ligase, and reversed by deubiquitinases. Depending on the enzymes, specific linkage types of ubiquitin chains are generated or hydrolyze...

Objective(s):Small ubiquitin-like modifiers (SUMOs) are a family of ubiquitin-related, proteins that are involved in a wide variety of signaling pathways. SUMOylation, as a vital post translational modification, regulate protein function in manycellular processes. Diazinon (DZN), an organophosphate insecticide, causses oxidative stress and subsequently programmed cell death in different tissues...

To downregulate cell signaling, eukaryotes modify plasma membrane receptors by ubiquitination (cargo) and deliver them via vesicles to the endosomal surfaces. Once at this location, cargo is delivered lysosomal lumen, where they are proteolyzed. The ubiquitin-binding protein TOM1 sorts through recognition of ubiquitin moieties its VHS GAT domains. phosphoinositide phosphatidylinositol 5-phospha...

Ubiquitin-specific protease (USP) 25, belonging to the USP family of deubiquitinases, harbors two tandem ubiquitin-interacting motifs (UIMs), a ~20-amino-acid α-helical stretch that binds to ubiquitin. However, the role of the UIMs in USP25 remains unclear. Here we show that the tandem UIM region binds to Lys48-, but not Lys63-, linked ubiquitin chains, where the two UIMs played a critical and ...

Lys48-linked ubiquitin chains act as the main targeting signals for protein degradation by the proteasome. Here we report selective binding of AIRAPL, a protein that associates with the proteasome upon exposure to arsenite, to Lys48-linked tri-ubiquitin chains. AIRAPL comprises two ubiquitin-interacting motifs in tandem (tUIMs) that are linked through a flexible inter-UIM region. In the complex...

The dynamic and reversible process of ubiquitin modification controls various cellular activities. Ubiquitin exists as monomers, unanchored chains, or protein-conjugated forms, but the regulation of these interconversions remains largely unknown. Here, we identified a protein designated Rfu1 (regulator of free ubiquitin chains 1), which regulates intracellular concentrations of monomeric ubiqui...