In mammalian cells, cyclin dependent kinase (CDK) is subjected to negative regulation by a conserved kinase, Wee1. In budding yeast, S. cerevisiae, Swe1 kinase, the Wee1 homologue, phosphorylates and inactivates Cdk1 associated with mitotic cyclins to prevent entry into mitosis. Both transcription and proteolysis ensure the periodic appearance of Swe1 protein during the cell cycle. To facilitate Swe1 protein degradation, the functional Hsl1-Hsl7 protein complex recruits Swe1 to the bud-neck. As a kinase, Hsl1 phosphorylates Hsl7 directly and this phosphorylation is essential for Swe1 degradation. Hsl1 itself is also a phosphoprotein and Elm1 kinase has been shown to be responsible for Hsl1 phosphorylation. Protein phosphatase 2A (PP2A) is a critical phosphatase involved in multiple cellular events. Previous work indicates that the absence of the B-regulatory subunit Cdc55 results in accumulation of Swe1 protein, which leads to the abnormal bud morphology. We present evidence indicating that the failure of Swe1 degradation in cdc55 mutants is a consequence of defective Hsl1-Hsl7 pathway. We found that the phosphorylation of both Hsl7 and Hsl1 deceased obviously in cdc55 mutant, suggesting the compromised kinase activity of Elm1. Moreover, casein kinases are also required for the phosphorylation and activation of Hsl1. / A Thesis submitted to the Department of Biomedical Science in partial fulfillment
of the requirements for the degree of Master of Science. / Degree Awarded: Summer Semester, 2010. / Date of Defense: July 15, 2010. / PP2A, Cdc55, Yck1, Yck2, Swe1 / Includes bibliographical references. / Yanchang Wang, Professor Directing Thesis; Wuming Deng, University Representative; Mary Hurt, Committee Member; Akash Gunjan, Committee Member; Hongguo Yu, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_168855 |
| Contributors | Wu, Jinsong (authoraut), Wang, Yanchang (professor directing thesis), Deng, Wuming (university representative), Hurt, Mary (committee member), Gunjan, Akash (committee member), Yu, Hongguo (committee member), Department of Biomedical Sciences (degree granting department), Florida State University (degree granting institution) |
| Publisher | Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource, computer, application/pdf |
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