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Poster Presentations
Day 4, June 25（Wed.）
Room P (Maesato East, Foyer, Ocean Wing)
- 4P-AM-43
Protein Terminomics-centric Analyses of Human Noncanonical Proteomes Reveal the Diversity of Human Proteoforms
(1Kyoto Univ., 2Institute of Science Tokyo, 3NIBIOHN)
oRiko Egawa1, Hiroshi Nishida1, Yuta Kochi2, Kosuke Ogata1, Yasushi Ishihama1,3
Translatome analysis based on ribosome profiling has led to the discovery of proteins translated from alternative open reading frames (ORFs) within mRNAs and non-coding RNAs. While methods for proteomic analysis of these noncanonical proteins have started to develop, technical difficulties in both measurement and analysis still prevent the comprehensive and reliable identification of noncanonical proteins and the understanding of their functions. In this study, we analyzed lymphoblastoid cell lines derived from 30 healthy individuals using liquid chromatography with tandem mass spectrometry (LC/MS/MS) to identify noncanonical proteoforms. Both the global proteome and the enriched terminome fraction were measured and analyzed using a custom database consisting of translated ORFs in the reference transcript database GENCODE in addition to canonical and predicted protein sequences registered in UniProtKB. As a result, we identified approximately 100 novel translation initiation sites within canonical proteins and 400 noncanonical proteins from alternative ORFs. Additionally, we identified changes in the C-terminal positions of several noncanonical proteins between cell lines, suggesting different proteolysis patterns between individuals that may lead to phenotypic changes.