Molecular characterization of SIG1, a Saccharomyces cerevisiae gene involved in negative regulation of G-protein-mediated signal transduction.
Two recessive mutations in the Saccharomyces cerevisiae SIG1 (suppressor of inhibitory G-protein) gene have been identified by their ability to suppress the signalling defect of dominant-negative variants of the mating response G-protein beta-subunit. The mutations and deletion of SIG1 enhance the sensitivity of the cells to pheromone and stimulate the basal transcription of a mating specific gene, FUS1, suggesting that Sig1p plays a negatively regulatory role in G beta gamma-mediated signal transduction. An additional function of Sig1p in vegetatively growing cells is suggested by the finding that the mutations and deletion of SIG1 cause temperature-sensitive growth defects. The SIG1 gene encodes a protein with a molecular weight of 65 kDa that contains at the amino-terminus two zinc finger-like sequence motifs. Epistasis experiments localize the action of Sig1p within the pheromone signalling pathway at a position at or shortly after the G-protein. We propose that Sig1p represents a novel negative regulator of G beta gamma-mediated signal transduction.
Biotechnology Research Institute, National Research of Canada, Montreal, Quebec.
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E
Leberer
D
D
Dignard
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D
Harcus
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M
Whiteway
D Y
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Thomas
D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004271:DNA, Fungal; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D005800:Genes, Fungal; D000072235:Mating Factor; D008565:Membrane Proteins; D020928:Mitogen-Activated Protein Kinases; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010455:Peptides / Q000494:pharmacology; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction / Q000235:genetics*; D044767:Ubiquitin-Protein Ligases
D004271:DNA, Fungal; C490024:FUS1 protein, S cerevisiae; D005656:Fungal Proteins; D008565:Membrane Proteins; D010455:Peptides; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D000072235:Mating Factor; C086923:MOT2 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases; D011505:Protein-Tyrosine Kinases; C075580:FUS3 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins