Abstract
The Saccharomyces cerevisiae phosphatidylinositol kinase homolog TOR2 is required for organization of the actin cytoskeleton. Overexpression of RHO1 or RHO2, encoding Rho-like GTPases, or ROM2, encoding a GDP/GTP exchange factor for RHO1 and RHO2, suppresses a tor2 mutation. Deletion of SAC7, a gene originally identified as a suppressor of an actin mutation, also suppresses a tor2 mutation. SAC7 is a novel GTPase-activating protein for RHO1. ROM2 exchange activity is reduced in a tor2 mutant, and overexpression of ROM2 lacking its PH domain can no longer suppress a tor2 mutation. Thus, TOR2 signals to the actin cytoskeleton through a GTPase switch composed of RHO1, RHO2, ROM2, and SAC7. TOR2 activates this switch via ROM2, possibly via the ROM2 PH domain.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Cell Cycle Proteins
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Cell Division / physiology
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Cell Polarity / physiology
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Cell Size / physiology
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DNA-Binding Proteins / chemistry
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Fungal Proteins / genetics
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Fungal Proteins / metabolism*
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GTP Phosphohydrolases / genetics
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GTP Phosphohydrolases / metabolism
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GTP-Binding Proteins / genetics
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GTP-Binding Proteins / metabolism*
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GTPase-Activating Proteins
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Gene Expression Regulation, Enzymologic / physiology
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Gene Expression Regulation, Fungal / physiology
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Guanine Nucleotide Exchange Factors*
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Guanosine Diphosphate / metabolism
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Guanosine Triphosphate / metabolism
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Leucine Zippers / physiology
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Molecular Sequence Data
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Monomeric GTP-Binding Proteins*
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Mutation / physiology
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Phosphatidylinositol 3-Kinases
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Phosphotransferases (Alcohol Group Acceptor) / genetics
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Phosphotransferases (Alcohol Group Acceptor) / metabolism*
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Plant Proteins / chemistry
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Plant Proteins / genetics
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Plant Proteins / metabolism*
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Protein Structure, Tertiary
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Proteins / metabolism
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Saccharomyces cerevisiae / cytology
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Saccharomyces cerevisiae / enzymology*
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae Proteins*
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Sequence Homology, Amino Acid
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Signal Transduction / physiology
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rho GTP-Binding Proteins*
Substances
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Cell Cycle Proteins
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DNA-Binding Proteins
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Fungal Proteins
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GTPase-Activating Proteins
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Guanine Nucleotide Exchange Factors
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Plant Proteins
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Proteins
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ROM2 protein, S cerevisiae
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SAC7 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Guanosine Diphosphate
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Guanosine Triphosphate
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Phosphotransferases (Alcohol Group Acceptor)
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TOR2 protein, S cerevisiae
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GTP Phosphohydrolases
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GTP-Binding Proteins
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Monomeric GTP-Binding Proteins
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RHO1 protein, S cerevisiae
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RHO2 protein, S cerevisiae
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rho GTP-Binding Proteins