Abstract
Maintenance of cellular integrity in Saccharomyces cerevisiae is carried out by the activation of the protein kinase C-mediated mitogen-activated protein kinase (PKC1-MAPK) pathway. Here we report that correct down-regulation of both basal and induced activity of the PKC1-MAPK pathway requires the SIT4 function. Sit4 is a protein phosphatase also required for a proper cell cycle progression. We present evidence demonstrating that the G(1) to S delay in the cell cycle, which occurs as a consequence of the absence of Sit4, is mediated by up-regulation of Pkc1 activity. Sit4 operates downstream of the plasma membrane sensors Mid2, Wsc1, and Wsc2 and upstream of Pkc1. Sit4 affects all known biological functions involving Pkc1, namely Mpk1 activity and cell wall integrity, actin cytoskeleton organization, and ribosomal gene transcription.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acacia
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Actins / metabolism
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Calcium-Binding Proteins / metabolism
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Carrier Proteins / metabolism*
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Carrier Proteins / physiology*
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Cell Cycle
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Cell Wall / metabolism
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Cytoskeleton / metabolism
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Down-Regulation
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G1 Phase
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Immunoblotting
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Intracellular Signaling Peptides and Proteins
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Membrane Glycoproteins
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Membrane Proteins / metabolism
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Mitogen-Activated Protein Kinases*
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Models, Biological
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Mutation
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Phosphoprotein Phosphatases*
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Plant Proteins / metabolism
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Precipitin Tests
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Protein Binding
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Protein Kinase C / metabolism*
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Protein Phosphatase 2
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Protein Serine-Threonine Kinases / metabolism
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Ribosomes / metabolism
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S Phase
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins / metabolism
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Temperature
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Time Factors
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Transcription, Genetic
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Trypsin Inhibitors / metabolism
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Up-Regulation
Substances
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Actins
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Calcium-Binding Proteins
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Carrier Proteins
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Intracellular Signaling Peptides and Proteins
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MID2 protein, S cerevisiae
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Membrane Glycoproteins
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Membrane Proteins
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Plant Proteins
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SLG1 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Trypsin Inhibitors
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WSC2 protein, S cerevisiae
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ACTI protein, Acacia confusa
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Protein Serine-Threonine Kinases
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Protein Kinase C
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Mitogen-Activated Protein Kinases
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SLT2 protein, S cerevisiae
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Phosphoprotein Phosphatases
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Protein Phosphatase 2
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SIT4 protein, S cerevisiae