Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.730626
Title: N.M.R. structural studies and modelling of modular proteins
Author: Downing, Anna Kristina
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 1993
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Abstract:
This thesis focuses on structural studies of the fibronectin type 1 module (F1) of tissue-type plasminogen activator (t-PA) and the N-terminal src homology 2 (SH2) module of the p85α subunit of phosphatidylinositol-3-OH kinase (PI3-kinase). t-PA plays a key role in the dissolution of blood clots. It is the only serine protease that binds to the fibrin network of a thrombus and localises its activity to the site of a clot. The t-PA F1 module is critical to t-PA fibrin binding. This module was produced for structural studies using a yeast alpha secretion system. N.m.r. data collected on the purified protein were used to calculate a high resolution structure of the module. The structures of the t-PA finger and the seventh type 1 module from human fibronectin were compared and found to be strikingly similar. Topological differences between the two molecules suggested that one face of the t-PA finger engages in domain-domain interactions in the intact protein. A model of the intact t-PA was constructed and used to explain differences in the biological activity of the two naturally abundant glycosylated variants of the molecule. The SH2 module binds sequence-specifically to intracellular phosphorylated tyrosines on receptor tyrosine kinases and thus mediates cell signalling pathways which lead ultimately to changes in cell growth and differentiation. The 3-dimensional structure of the N-terminal SH2 of the p85α subunit of PI3-kinase was computed and compared to the v-src SH2 complexed with low affinity phosphopeptides in order to assess the conformational changes associated with phosphopeptide binding. Finally, the structures of two homologous SH2 modules were modelled to identify possible high affinity protein-peptide interactions responsible for the variation in phosphopeptide affinity of SH2 modules. The predicted interactions were subsequently observed in two high affinity SH2-peptide complexes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.730626  DOI: Not available
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