| Summary: | 碩士 === 國立中山大學 === 生物科學系研究所 === 93 === Abstract:
TSG101 is a tumor susceptibility gene exhibits multiple biological function, including the regulation of cell progression, intracellular protein sorting and membrane trafficking, and transcription activity of nuclear recptor such as estrogen recptor. TSG101 contains an UBC domain which is homologous to that in ubiquitin conjugating E2 enzyme. However, it lacks an essential cysteine residue, which is essential for catalytic activity. Cellular protein ubiquitination serves as a signal for protein degradation or sorting into multivesicular body. UBC domain of TSG101 was proved to contain amino acid residues that are important for its interaction with ubquitin (residues V43, N46, D46 and F88) and PTAP sequence found in the late domain of HIV gag protein (residues Y63, M95, V141). SUMO is an ubquitin-like modifier which can modify cellular protein harbors ΨKXE amino acid sequence, thereby change its subcellular localization and biological activities. TSG101 protein contains K98, K243, K264 and K269 residues that localize in potential SUMO modification site. Our preliminary data indicated that TSG101 colocalize with SUMO in nucleus. It is interesting to know whether TSG101 is sumoylated, and its functional significance. In this thesis, a series of site-directed mutageneic mutant HA and GFP-tagged expression plasmids which contain mutation of the above mentioned functional related amino acid residues were constructed for future TSG101 functional studies.
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