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Ubiquitin Lab Report

Decent Essays

Cell homeostasis is a complex yet strictly regulated by many regulators. Different from big role-player such as enzymes in many signaling pathways, the universal consensus of small regulator ubiquitin contributes a great length to the of the complex post translational regulating protein system. Consisting of 76-residue protein, ubiquitin not only highly expresses in cell for various signal transduction pathways, it also is one of the most resilience and packed protein that is highly conserved among the eukaryotes[1]. Ubiquitin is firstly produced intracellularly as precursor fusion protein chain consisting polyubiquitin or ubiquitin fused to amino-terminus of Ribosomal protein 40S and 60S units; the generation of free ubiquitin from these precursor …show more content…

The de-ubiquitinase (DUB) will cleave this precursor into free monomer ubiquitin molecules and can be activated and attached to the target protein through ATP dependent process called ubiquitination with the help of activating enzyme E1, conjugating enzyme E2, and ligase E3. Through forming (iso)-peptide, thioester, or ester bond between carboxyl groups of C-terminal glycine 76 on ubiquitin and the ε-amino group of the lysine, cysteine, serine/threonine on the substrate, respectively, the poly-ubiquitin chain is formed [3]. Based on the different internal Lysine (Lys6, Lys11, Lys27, Lys29, Lys33, Lys48, and Lys63) and on the proximal ubiquitin, the (iso)-peptide bond can be form with another ubiquitin, distal mono-ubiquitin [4, 5]. Consequently, seven conventional poly-ubiquitin chains resulting in different 3-dimentional shapes explaining its different characteristics inherited upon binding to the target protein [5, 6]. With ranging more than 500 putative E3 ligases exist in human, the E3 ligase will tag the poly-ubiquitin chain to the target protein with high specificity

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