Ubiquitin and ubiquitinationINTRODUCTIONGeneral understanding of ubiquitin.Ubiquitin is a regulatory protein that plays an important role in the regulation of eukaryotic cells. The word ubiquitin is derived from the Latin word, omnipresent, which means everywhere, since this protein is found in all parts of the body. It was first isolated by Goldstein in 1975 from the thymus and was subsequently found in all tissues and organs of eukaryotic cells1. The protein has a molar mass of 8.5 kDa and consists of 76 amino acids that are highly conserved in all eukaryotic organisms1. There are four genes in the human genome that are responsible for ubiquitin production, including UBB, UBC, UBA52, and RPS27A. Although ubiquitin is only found in eukaryotes, prokaryotes have a similar protein that performs the same function as ubiquitin, known as ThiS 1. Figure 1 Basic structure of ubiquitin The structure of ubiquitin Ubiquitin is characterized by an N terminal and a C terminal as a regular protein. Lys 63 and Lys 48 (Figure 1) play important roles in ubiquitination (shown below), the step in post-translational modification where ubiquitin attaches to target proteins. This process is extremely important because it determines the function of protein 2. Ubiquitination is the step in post-translational modification where ubiquitin attaches to target proteins. Ubiquitin plays an important role in post-translational modification, the process that determines a protein's function. Post-translational modification can be phosphorylation, SUMOlation and ubiquitination. 3. Ubiquitination was initially only associated with protein degradation, now ubiquitination has been connected to other cellular functions. There are three enzymes that make ubiquitination possible, namely E1 (the ubiquitin-activating enzyme), E2 (the ubiquitin-conjugating enzyme), and E3 (the ubiquitin ligase) 3. This article will be a summary of ubiquitin structure, function, steps of ubiquitination, and application to cancer research.2) Similarities and differences of the ubiquitin family; StructureThe ubiquitin family is large, but shares some characteristics. Some of these features include: ubiquitin folding and the biochemical mechanism they use to bind to the target protein. The structure of ubiquitin was analyzed as part of a larger NMR study aimed at understanding new techniques, including H/D exchange. This technique has mainly contributed information on protein folding.