Characterization of posttranslational modifications of cellular hnRNPK protein using an in vivo biotinylation system

• Main Authors: Chieh-Hsin Yang, 楊婕鑫
• Other Authors: Chao-Hsiung Lin
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/60632578826814663220

碩士 === 國立陽明大學 === 生命科學暨基因體科學研究所 === 99 === Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is an abundant nuclear RNA-binding protein that participates in a wide array of cellular processes, including chromatin remodeling, transcription, RNA splicing, translation, and mRNA stability. In our previous study, hnRNPK was found widely present in different locations of 2D gels, which is likely due to the many hnRNPK isoforms arisen from combination of diverse post-translational modifications (PTMs). However, the regulation of hnRNPK activity remains unclear but several studies implicated that diverse PTMs of hnRNPK play an important role in regulating its function. I therefore established an in vivo protein biotinlyation system to collect sufficient amount of cellular proteins for subsequent mass-spectrometric analysis of PTMs. Based on the co-expression of a target gene fused with a short biotin acceptor domain (BAP) and an E. coli biotin ligase, BirA, I were able to produce and further purify a biotinylated hnRNPK in mammalian cells. Currently, I can identify several known and unknown PTMs of hnRNPK, including five dimethylated arginines, four phosphorylated serines and one phosphorylated tyrosine. In addition, I have used this methodology to monitor PTM changes of hnRNPK between different cell lines or under diverse stimulations to investigate the mechanism how PTMs of hnRNPK regulate its functions.