The role of Yck1,2 casein kinase 1 in the trafficking and glucose induced inactivation of maltose permease in Saccharomyces cerevisiae.
Item
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Title
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The role of Yck1,2 casein kinase 1 in the trafficking and glucose induced inactivation of maltose permease in Saccharomyces cerevisiae.
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Identifier
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AAI3144096
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identifier
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3144096
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Creator
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Gadura, Nidhi.
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Contributor
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Adviser: Corinne A. Michels
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Date
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2004
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Molecular | Biology, Cell
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Abstract
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In Saccharomyces, glucose induces proteolysis of maltose permease that requires endocytosis, vesicle sorting and the vacuolar degradation enzymes, moreover, it is ubiquitin mediated. This dissertation continues the investigation of the mechanisms of this process and demonstrates the essential role of Yck1, 2 casein kinase 1.;Site-specific mutations of phosphorylatable Ser/Thr in the N-terminal PEST sequence dramatically slows the proteolysis but does not alter the ability of this protein to localize to the plasma membrane or its rapid glucose-induced loss of maltose transport activity. Altering a putative dileucine [D/EExxxLL/I] motif (involved in protein sorting) and a dilysine motif (putative ubiquitin conjugation sites) in the PEST sequence causes significant defects in maltose transport activity, mislocalization to a PVC and resistance to glucose-induced inactivation. Also in doa4Delta strain (depletes available ubiquitin) Mal61p localizes to the plasma membrane, remains hyperphosphorylated and transports actively. However, there is no glucose-induced inactivation, implying that ubiquitination at the plasma membrane is required for endocytosis of Mal61p.;Yeast casein kinase 1, encoded by YCK1 and YCK2, is involved in endocytosis of several integral membrane proteins. We used strain yck1Deltayck2-ts and an akr1Delta (defective in the localization of Yck1,2 kinase to the plasma membrane), to explore the role of Yck1,2 kinase in Mal61p glucose-induced inactivation. The results show that yck-ts strains exhibit significantly reduced ability to transport maltose and no impairment of its localization to the cell surface however glucose-induced inactivation is blocked. Overexpression of YCK2 in doa4Delta does not restore glucose-induced inactivation of Mal61p indicating that YCK1, 2 is upstream of DOA4.;Our previous study observed that glucose-induced inactivation in a reg1Delta strain is blocked and that phosphorylation of Mal61p decreases suggesting that Reg1p-Glc7p phosphatase acts indirectly on maltose permease and that there is a kinase intermediate that regulates phosphorylation. reg1Delta and yck-ts strains exhibit similar phenotypes regarding Mal61p localization, phosphorylation, and resistance to glucose-induced inactivation suggesting that these regulations are components of a common signaling pathway. Epistasis analysis is used to establish that REG1 is upstream of YCK1,2 in a novel Glc7-Reg1 phosphatase---Yck1,2 kinase in the signaling pathway controlling glucose-induced inactivation of maltose permease.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
