The SIT4 protein phosphatase functions in late G1 for progression into S phase

Sutton, A., Immanuel, D., Arndt, K. T. (April 1991) The SIT4 protein phosphatase functions in late G1 for progression into S phase. Mol Cell Biol, 11 (4). pp. 2133-48. ISSN 0270-7306 (Print)0270-7306 (Linking)

DOI: 10.1128/MCB.11.4.2133


Saccharomyces cerevisiae strains containing temperature-sensitive mutations in the SIT4 protein phosphatase arrest in late G1 at the nonpermissive temperature. Order-of-function analysis shows that SIT4 is required in late G1 for progression into S phase. While the levels of SIT4 do not change in the cell cycle, SIT4 associates with two high-molecular-weight phosphoproteins in a cell-cycle-dependent fashion. In addition, we have identified a polymorphic gene, SSD1, that in some versions can suppress the lethality due to a deletion of SIT4 and can also partially suppress the phenotypic defects due to a null mutation in BCY1. The SSD1 protein is implicated in G1 control and has a region of similarity to the dis3 protein of Schizosaccharomyces pombe. We have also identified a gene, PPH2alpha, that in high copy number can partially suppress the growth defect of sit4 strains. The PPH2 alpha gene encodes a predicted protein that is 80% identical to the catalytic domain of mammalian type 2A protein phosphatases but also has an acidic amino-terminal extension not present in other phosphatases.

Item Type: Paper
Uncontrolled Keywords: Amino Acid Sequence Base Sequence Cytoplasm/enzymology Fluorescent Antibody Technique *G1 Phase Genes Molecular Sequence Data Molecular Weight Mutation Phenotype Phosphoprotein Phosphatases/*genetics/metabolism Polymorphism, Genetic Precipitin Tests Protein Phosphatase 2 *S Phase Saccharomyces cerevisiae/enzymology/*genetics/growth & development Saccharomyces cerevisiae Proteins Sequence Homology, Nucleic Acid Temperature
Subjects: organs, tissues, organelles, cell types and functions > cell types and functions > cell functions > cell cycle
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > enzymes > protein phosphatase
CSHL Authors:
Communities: CSHL labs
Depositing User: Matt Covey
Date: April 1991
Date Deposited: 10 Dec 2015 20:15
Last Modified: 10 Dec 2015 20:15
PMCID: PMC359901
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