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Molecular interactions mediated by the surface antigen CD5 during T lymphocyte activation
Thesis (M.M.S. (Medical Biochemistry)) -- University of Stellenbosch, 1996.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867613865219457024 |
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| access_status_str | Open Access |
| author | Broszeit, Richard |
| author2 | Beyers, A.D. |
| author_browse | Beyers, A.D. Broszeit, Richard |
| author_facet | Beyers, A.D. Broszeit, Richard |
| author_sort | Broszeit, Richard |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (M.M.S. (Medical Biochemistry)) -- University of Stellenbosch, 1996. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/55172 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:42:55.322Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/55172 Molecular interactions mediated by the surface antigen CD5 during T lymphocyte activation Broszeit, Richard Beyers, A.D. Stellenbosch University. Faculty of Science. Dept. of Biochemistry. CD antigens T cells Cell receptors Dissertations -- Medicine Thesis (M.M.S. (Medical Biochemistry)) -- University of Stellenbosch, 1996. T lymphocyte activation is initiated when the T cell receptor (TCR) which is associated with transmembrane proteins such as CD3, CD4, CD8 and CD5, recognises foreign antigen bound to an MHC molecule on an antigen presenting cell. Binding of the TCR to antigen gives rise to activation of the tyrosine kinases Lek and Fyn, which phosphorylate several TCR-associated proteins, creating docking sites for molecules such as phospharydilinositol 3'-kinase (PI3-kinase) and ZAP-70. This interaction takes place via SH2 domains, which bind to conserved phosphotyrosine-containing motifs with high affinity and specificity, PI3-kinase, comprising a catalytic 110 kDa and a regulatory 85 kDa subunit with two SH2 domains, phosphorylates phosphoinositides at the D3 position, which has been associated with mitogenesis. ZAP-70 binds to phosphorylated Immunoreceptor Tyrosine Activation Motifs (ITAMs) on D3 ? and ? chains via tandem SH2 domains. CD5 contains an ITAM-like sequence and is phosphorylated by Lek following T-cell stimulation. PI3-kinase activity associated with CD5 in stimulated T cells has been demonstrated, and the mechanism by which this association could take place was investigated. A model was proposed in which the p85 subunit of PI3-kinase interacts with CD5 via a linker molecule. Candidate linker molecules are Lek and ZAP-70, since both contain SH2 domains which could bind to the ITAM-like motif of CD5, as well potential binding motifs for the SH2 domains of p85. The SH2 domains of Lek, ZAP-70 and p85 were expressed GST fusion protein in E. colt. Fusion proteins bound to beads were added to T cell lysates, and binding proteins were visualised by anti-phosphotyrosine Western blotting. Proteins of various molecular weights were precipitated by the SH2 domains of Lek, 7AP-70 and p85 from resting and stimulated cells, Furthermore, the SH2 domains of Lek, as well as the C-terminal SH2 domain of p85, are in vitro substrates for coprecipitated kinases. CD5 was immunoprecipitated from lysates of T cells and kinase assays were performed on the immune complexes. CD5 immune complex kinase assay products were subjected to reprecipitation using specific antibodies, which demonstrated the presence of ZAP-70 in CD5 immune complexes. Reprecipitations of CD5 kinase assay products using GST-SH2 fusion proteins were performed. CD5-associated proteins of 70, 24 and 21 kDa are binding proteins for an array of SH2 domains in vitro. Work is under way to investigate the specificity of SH2 domain interactions with CD5-associated molecules using competition assays. Masters 2012-08-27T11:36:55Z 2012-08-27T11:36:55Z 1996 Thesis http://hdl.handle.net/10019.1/55172 en_ZA Stellenbosch University 179 pages : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | CD antigens T cells Cell receptors Dissertations -- Medicine Broszeit, Richard Molecular interactions mediated by the surface antigen CD5 during T lymphocyte activation |
| title | Molecular interactions mediated by the surface antigen CD5 during T lymphocyte activation |
| title_full | Molecular interactions mediated by the surface antigen CD5 during T lymphocyte activation |
| title_fullStr | Molecular interactions mediated by the surface antigen CD5 during T lymphocyte activation |
| title_full_unstemmed | Molecular interactions mediated by the surface antigen CD5 during T lymphocyte activation |
| title_short | Molecular interactions mediated by the surface antigen CD5 during T lymphocyte activation |
| title_sort | molecular interactions mediated by the surface antigen cd5 during t lymphocyte activation |
| topic | CD antigens T cells Cell receptors Dissertations -- Medicine |
| url | http://hdl.handle.net/10019.1/55172 |
| work_keys_str_mv | AT broszeitrichard molecularinteractionsmediatedbythesurfaceantigencd5duringtlymphocyteactivation |