Ubiquitin G76A Human

Ubiquitin is a small, highly conserved regulatory protein found in all eukaryotic cells. It plays a crucial role in various cellular processes, primarily through its attachment to other proteins, a process known as ubiquitination. This post-translational modification can signal for protein degradation, alter protein activity, or affect protein localization.

Ubiquitin consists of 76 amino acids and has a molecular weight of approximately 8.5 kDa. The protein is highly conserved across species, with human ubiquitin sharing 96% sequence identity with yeast ubiquitin and 100% with mouse ubiquitin . The C-terminal glycine residue (G76) is critical for its function, as it forms an isopeptide bond with lysine residues on target proteins during ubiquitination.

The G76A mutation involves substituting the glycine residue at position 76 with alanine. This mutation significantly impacts ubiquitin’s function. Specifically, it inhibits the activity of ubiquitin hydrolases, enzymes responsible for removing ubiquitin from protein conjugates . As a result, ubiquitin G76A becomes irreversibly attached to target proteins, preventing their deubiquitination and altering the balance between free and conjugated ubiquitin .

Recombinant human ubiquitin G76A is produced using bacterial expression systems, typically in E. coli. The protein is purified through ion-exchange chromatography to ensure high purity . It is often tagged with a poly-histidine sequence to facilitate purification and detection .

Recombinant ubiquitin G76A is primarily used in research to study the ubiquitin-proteasome system. It serves as a negative control in ubiquitination assays, helping to elucidate the roles of various enzymes involved in ubiquitin conjugation and deubiquitination . Additionally, it is used to investigate the effects of impaired deubiquitination on cellular processes and protein stability .

Recombinant ubiquitin G76A is temperature-sensitive and should be stored at -80°C to prevent degradation. It is recommended to avoid repeated freeze-thaw cycles and to keep the protein on ice when not in storage .