Ubiquitination provides a means of rapidly and irreversibly eliminating an unwanted protein from the cell, and is therefore a potentially effective tool for regulating cellular behaviour. Ubiquitin-mediated proteolysis is involved in such diverse physiological functions as growth control, cell signalling, differentiation and the immune response. The aim of this research has been to investigate its role in <i>Drosophila </i>embryogenesis. Protein ubiquitination is a stepwise process carried out by three classes of enzyme known as E1s, E2s and E3s. The E1 (ubiquitin-activating enzyme), generates a thiolester linkage with a ubiquitin cysteine residue. The activated ubiquitin is then transferred to an E2 (ubiquitin-conjugating enzyme) which, with the help of an E3 (ubiquitin-protein ligase), recruits the substrate protein which is to be degraded. I examined the embryonic expression patterns of several known and novel genes encoding each type of ubiquitinating enzyme. The E2 <i>UbcD4</i> is transcribed during early to mid-embryogenesis in a variety of tissues, with specific germcell expression in stage 10 embryos. This suggested a possible role for UbcD4 in germ cell migration towards the somatic gonadal precursors. <i>UbcD4 </i>mRNA was also abundant in git and nervous system during germband retraction and dorsal closure. I screened for UbcD4 - interacting proteins using the yeast two-hybrid system, and identified several putative substrates for, as well as ancillary factors involved in, ubiquitination by UbcD4. These included a novel E3 of the Hect-domain family. In an attempt to examine the function of UbcD4 directly, I used RNA interference to disrupt <i>UbcD4</i> function. The results suggest a post-germband retraction requirement for UbcD4.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:642578 |
| Date | January 2000 |
| Creators | Canning, Mary |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13305 |
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