PTMScan^® HS Ubiquitin/SUMO Remnant Motif (K-ε-GG) Kit

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Background

Ubiquitin is a conserved polypeptide unit that plays an important role in the ubiquitin-proteasome pathway. Ubiquitin can be covalently linked to many cellular proteins by the ubiquitination process, which targets proteins for degradation by the 26S proteasome. Three components are involved in the target protein-ubiquitin conjugation process. Ubiquitin is first activated by forming a thiolester complex with the activation component E1; the activated ubiquitin is subsequently transferred to the ubiquitin-carrier protein E2, then from E2 to ubiquitin ligase E3 for final delivery to the epsilon-NH2 of the target protein lysine residue (1-3). The ubiquitin-proteasome pathway has been implicated in a wide range of normal biological processes and in disease-related abnormalities. Several proteins such as IκB, p53, cdc25A, and Bcl-2 have been shown to be targets for the ubiquitin-proteasome process as part of regulation of cell cycle progression, differentiation, cell stress response, and apoptosis (4-7).

Small ubiquitin-related modifier 1, 2, and 3 (SUMO-1, -2, and -3) are members of the ubiquitin-like protein family (8). The covalent attachment of the SUMO-1, -2, or -3 (SUMOylation) to target proteins is analogous to ubiquitination.

Ubiquitin and the individual SUMO family members are all targeted to different proteins with diverse biological functions. Ubiquitin predominantly regulates degradation of its target (8). In contrast, SUMO-1 is conjugated to RanGAP, PML, p53, and IκB-α, regulates nuclear trafficking, forms subnuclear structures, and regulates transcriptional activity and protein stability (9-13). SUMO-2/-3 forms poly-(SUMO) chains, is conjugated to topoisomerase II and APP, regulates chromosomal segregation and cellular responses to environmental stress, and plays a role in the progression of Alzheimer's disease (14-17).