Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.653434
Title: Post-translational regulation of Mad3p in Saccharomyces cerevisiae
Author: King, Emma
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2005
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Abstract:
Mad3p is a component of the spindle checkpoint in Saccharomyces cerevisiae. Mad3p is known to be in a constitutive complex with another checkpoint component Bub3p and upon checkpoint activation it interacts with Mad2p and Cdc20p to form the mitotic checkpoint complex. Recent analysis also suggests that the Mad proteins, in addition to the direct inhibition of Cdc20p through formation of the mitotic checkpoint complex, have an additional role in the down-regulation of Cdc20p levels in the cell. The results presented in this thesis show Mad3p to be a protein that is phosphorylated during every mitosis and consequently upon spindle checkpoint activation. Such phosphorylation does not require any other checkpoint components. Experiments also show that Mad3p is phosphorylated on serine 337 by Ipllp kinase in vitro and the phosphorylation of Mad3p in vivo, due to an absence of tension at the kinetochore, requires Ipllp. Mad3p contains two KEN box motifs that are conserved between species. Evidence in this thesis demonstrates that mutation of either of these KEN boxes renders cells sensitive to microtubule depolymerising drugs. Further analysis of these mutants shows that Cdc20p binding is reduced in both but they can both still bind Bub3p. Mutation of the N-terminal KEN box increases the half-­life of Cdc20p and consequently the total levels of Cdc20p in the cell. Cdc20p turnover is also reduced in the absence of Bublp and Bub3p, but to a lesser extent. Mutation of the second KEN box in Mad3p leads to a dominant phenotype that perturbs mitosis even in the presence of wild­type Mad3p.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.653434  DOI: Not available
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