Members of the eukaryotic initiation factor 4G (eIF4G) family play a central role in the translation initiation process. One member of this family is p97 (also called DAP5 and NAT1), a protein that is highly homologous to the C-terminal two thirds of eIF4G. Overexpression studies suggested that p97 is a pure translational repressor that has to be cleaved into a shorter form called p86, in order to show translational activity. In this study a series of experiments indicated that full length p97 has a number elF property such as association with active translating ribosomes, stimulatory effects in the Direct Initiation Factor assay and accumulation in stress granules. Additionally the endogenous p97 complex was isolated from HeLa cells and mRNA as well as the protein components were characterized. P97 associated mRNAs were described by a custom made 5'UTR focus array, showing that the protein binds to a broad range of mRNA. The relative lack of mRNA specificity argues for a general role of p97 in translation, which does not seems to be essential in unchallenged cells, because a down regulation of p97 protein levels has no effect on the translational status of the bulk of mRNAs. Mass spectrometry analysis revealed a novel protein-protein interaction between p97 and DNA methyltransferase 1 (Dnmt1), which does not rely on a nucleic acid. For this interaction the C- and N-terminus of p97 play a critical role. Further, Dnmt1 has the ability to interact with elF4G and the small ribosomal subunit, which might provide evidence for a novel function of Dnmt1 in RNA metabolism.
| Identifer | oai:union.ndltd.org:ADTP/258453 |
| Date | January 2008 |
| Creators | Nousch, Marco, Biotechnology & Biomolecular Sciences, Faculty of Science, UNSW |
| Publisher | Awarded by:University of New South Wales. Biotechnology & Biomolecular Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Nousch Marco., http://unsworks.unsw.edu.au/copyright |
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