PrP undergoes three major post-translational changes, N-terminal cleavage, N-linked glycosylation and the cleavage of a C-terminal peptide with the subsequent addition of a phosphatidylinositolglycolpipid (GPI-anchor), which is responsible for the protein's attachment to the membrane (ref, Stahl 1987). Most PrP<SUP>sc</SUP> appears to have an intact GPI-anchor although it cannot be released from tissue culture cells by the action of PIPLC as the wild-type can (Stahl 1990). However, 15% of PrP<SUP>sc</SUP> from hamster brain has been shown to be truncated at amino acid 228, these proteins having no GPI-anchor (Stahl 1990). The significance of these truncated proteins has not yet been elucidated. It is possible that the presence of a small amount of an abnormal, truncated protein could act as a seed for a conformational change that would result in the conversion of PrP<SUP>c</SUP> to PrP<SUP>sc</SUP> (Prusiner 1991). This project sets out to investigate the differences between the cellular processing of the wild type GPI-anchored protein and a mutant protein where addition of the GPI has been prevented. The mutant is investigated to show that the engineered mutation does indeed give rise to a GPI-less form and the size, glycosylation status, immunoreactivity and cellular location of the two proteins are investigated firstly in a cell-free system and secondly in tissue culture cells. The question of whether PrP<SUP>sc</SUP> can be produced when the GPI-anchor is absent will be addressed by subsequent studies of these mutations in transgenic mice.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:643325 |
| Date | January 1994 |
| Creators | Coleman, Michele |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/11998 |
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