The yeast phosphatidylinositol kinase homolog TOR2 activates RHO1 and RHO2 via the exchange factor ROM2.
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.
Schmidt
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Department of Biochemistry, Biozentrum, University of Basel, Switzerland.
Bickle
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Beck
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Hall
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D018797:Cell Cycle Proteins; D002455:Cell Division / Q000502:physiology; D016764:Cell Polarity / Q000502:physiology; D048429:Cell Size / Q000502:physiology; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D020662:Guanine Nucleotide Exchange Factors; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D016350:Leucine Zippers / Q000502:physiology; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins; D009154:Mutation / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000502:physiology; D020741:rho GTP-Binding Proteins
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D020559:Monomeric GTP-Binding Proteins; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D010940:Plant Proteins; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; D020741:rho GTP-Binding Proteins; C490929:ROM2 protein, S cerevisiae; C490634:SAC7 protein, S cerevisiae; C081135:TOR2 protein, S cerevisiae; C051302:RHO1 protein, S cerevisiae; C051303:RHO2 protein, S cerevisiae