| Summary: | 碩士 === 國立陽明大學 === 生化暨分子生物研究所 === 105 === Ribosome is a cytoplasmic complex made by ribonucleic acids and proteins that form a factory for protein synthesis in living cells. Besides protein synthesis, ribosomal protein are reported to be involved in cell proliferation, cell differentiation, DNA repair and cell apoptosis. In view of structure-function relationship of ribosome, previous studies show that protein modifications of specific ribosomal proteins are regulated under different conditions. While there are a diverse type of protein modifications present in cells, there were no studies on the overall modification profiles of ribosomal proteins. The lack of such information is probably due to the fact that most methodologies target a specific type of protein modification, rather than universally as many types as possible.
In chapter II, in order to investigate how PTMs of ribosomal proteins are involved in ribosomal function, we isolated ribosomal fraction from HeLa cells for their PTM characterization and mass spectrometric analyses helped verifies the adequate purity of these isolated ribosomes. We employed segmental average mass spectrum approach to screen possible modified peptides, and Criterion1 macro and DrawMS2 are applied to verify these candidates. Nearly three hundreds of verified modified peptides from twelve different PTM types are identified. Some of these tandem mass spectra have been annotated, which largely confirms the high confidence of our high-through screening approach. Finally, the high abundances of several types of protein modification indeed implicate their significance in regulation of ribosomal activities. We also discuss how our approach can help identify the protein modifications key to regulation of ribosomal activities.
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