title: Drosophila protein phosphatase V functionally complements a SIT4 mutant in Saccharomyces cerevisiae and its amino-terminal region can confer this complementation to a heterologous phosphatase catalytic domain.
abstract: The sequence of a Drosophila melanogaster cDNA encoding a novel 35 kDa protein serine/threonine phosphatase, termed PPV, is presented. PPV is 40-41% identical to Drosophila PP1, 53% identical to Drosophila PP2A and 63% identical to Saccharomyces cerevisiae SIT4. Complementation studies demonstrated that PPV can functionally rescue a temperature sensitive mutant of SIT4, a protein phosphatase required for the G1 to S transition of the cell cycle. When placed under the SIT4 promoter, PPV cDNA is able to replace the SIT4 gene in S. cerevisiae. The amino-terminal domain of PPV fused to another phosphatase catalytic region (PP1) also rescues the temperature sensitive SIT4 mutant and the SIT4 deletion mutant, implicating this region in binding to regulatory subunits and/or altering specificity. In Drosophila, a substantial transient increase in both PPV mRNA and protein occurs in late syncytial and early cellular blastoderm embryos. At the latter stage PPV is localized to the cytoplasm of cells at the cortex. This increase in PPV correlates with introduction of the G2 phase of the cell cycle, elevated zygotic transcription and cellularization, indicating that PPV may play a role in one or more of these processes.
authors.affiliation: Department of Biochemistry, The University, Dundee, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Mann
authors.forename: V
authors.initials: V
authors.lastname: Dombrádi
authors.forename: P T
authors.initials: PT
authors.lastname: Cohen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D002384:Catalysis; D002874:Chromosome Mapping; D004247:DNA; D004331:Drosophila melanogaster / Q000201:enzymology* / Q000235:genetics; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D054648:Protein Phosphatase 2; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; C104343:SIT4 protein, S cerevisiae