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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The Investigation of Cleavage Factor IM by Crystallographic and Biochemical Techniques

Coseno, Molly 01 January 2009 (has links)
RNA maturation involves several steps prior to export of the mRNA out of the nucleus and translation in the cytoplasm. PremRNA 3’end processing is one of such steps, and comprises the endonucleolytic cleavage and polyadenylation of the 3’end of the premRNA. These two steps involve more than 14 processing factors that coordinate multiple proteinprotein and proteinRNA interactions necessary to coordinate efficient cleavage and polyadenylation. To date, many of these interactions have been investigated biochemically and require additional structural characterization both to confirm and highlight key residues involved in substrate contacts. Further structural characterization will also open investigation into the mechanism of 3’end processing by providing structural insight into the coordination of multiple binding components. The cleavage factor Im, CF Im, is a component of the 3’end processing machinery and plays an important role early, during endonucleolytic cleavage, and additionally to increase polyadenylation efficiency and regulate poly(A) site recognition. CF Im is composed of a small 25 kDa subunit, CF Im25, and a large, either 58 kDa, 68 kDa, or 72 kDa subunit. The 25 kDa subunit of CF Im interacts with both the RNA and other processing factors such as the poly(A) polymerase, Clp1, and the larger subunit of CF Im. It is our goal to crystallize CF Im25 alone and in complex with one of its interacting partners to better understand CF Im25 contributions to premRNA 3’end processing. The structural investigation of CF Im25 and its binding partners has accomplished four major objectives: 1) Characterized the crystal structure of CF Im25 alone and bound to diadenosine tetraphosphate, 2) Provided insight into the oligomeric state of the CF Im complex, 3) Determined the binding properties of the Nudix domain of CF Im25 and its function in 3’end processing, 4) Further characterize the interactions between CF Im25 and PAP, CF Im68, and Clp1. These results demonstrate CF Im25 is a dimer both in solution and in the crystal suggesting that it is likely to be a dimer in the CF Im complex. The nucleotide binging capability of CF Im25 has no apparent role in 3’end processing in vitro but may provide a function outside of 3’end processing or may directly be involved in RNA recognition. The additional investigation of complex interactions with the 25 kDa subunit of CF Im25 suggests that although these factors interact during the 3’end processing event additional mechanisms may play a role in stabilizing those interactions.
2

From outsider to insider: how creative professional service firms internationalise

McQuillan, Deirdre, Scott, P.S., Mangematin, V. 23 May 2018 (has links)
yes / Purpose – The management of reputation and status is central to creative professional service firms (CPSFs) rendering the internationalisation process a particular challenge. We build on arguments that internationalisation requires moving from outsidership to insidership within client networks and focus on how CPSFs build signals about quality to start this process. Design/methodology/approach – The exploration draws from the international business, professional services and organizational status bodies of literature. A multiple case study design is developed comprising ten Irish architecture firms. In-depth semi-structured interviews were conducted. Findings - The findings clarify how relationships start in the internationalisation process through signal building. This allows firms to join client networks moving from outsidership to insidership. Our findings systemise three different approaches for CPSFs: from outsidership to insidership within a local market network, within a global industry network and within a global project network. Research Limitations/Implications – Research within other sectoral and geographical contexts could support transferability of the findings. Practical implications – The study has implications for CPSF’s international business strategies as it identifies multiple paths to gaining network insidership and the tactics employed to achieve this.

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