| Summary: | 碩士 === 慈濟大學 === 分子生物及細胞生物研究所 === 92 === Abstract Recent reports suggested that phosphatase of regenerating liver (PRL-3) might be involved in colorectal carcinoma metastasis with gene amplification. PRL-3 mRNA expression was elevated in nearly all metastatic lesions derived from colorectal cancers, regardless of the site of metastasis (liver, lung, brain, or ovary). PRL-3 is also a protein tyrosine phosphatase. The molecule has prenylation motif at the C terminus. When the prenylation site is removed, the PRL-3 can be found to translocate to the nucleus. It may involve in dephosphorylating its substrates that is related to cell motility. One of the possibilities is that substrates or cofactors that could interact with PRL-3 to facilitate its functions. In order to identify PRL-3 associated proteins we used the yeast two-hybrid system to screen the proteins which interact with human PRL-3. The results of screening showed that ribosomal protein S5 (207 amino acids) and a small peptide (65 amino acids) related to small cell lung carcinoma may interact with PRL-3. We found that these two proteins can interact with PRL-3 by using in vitro translational products of these two proteins and carried out the pull-down assay with GST fussed PRL-3. We also found that the prenylation site of PRL-3 can interact with a small peptide related to small cell lung carcinoma and this peptide may enhance the tyrosine phosphatase activity of PRL-3. Together, these results provide evidence that PRL-3 plays a causal role in tumor metastasis.
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