scholarly journals Drosophila mutants in the 55 kDa regulatory subunit of protein phosphatase 2A show strongly reduced ability to dephosphorylate substrates of p34cdc2

1994 ◽  
Vol 107 (9) ◽  
pp. 2609-2616 ◽  
Author(s):  
R.E. Mayer-Jaekel ◽  
H. Ohkura ◽  
P. Ferrigno ◽  
N. Andjelkovic ◽  
K. Shiomi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Phosphatase Activity ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Regulatory Subunit ◽  
Gene Encoding ◽  
Brain Extracts ◽  
Drosophila Protein ◽  
Phosphatase 2A ◽  
Drosophila Mutants

The 55 kDa regulatory subunit of Drosophila protein phosphatase 2A is located in the cytoplasm at all cell cycle stages, by the criterion of immunofluorescence. We are unable to detect significant change in protein phosphatase activity during the nuclear division cycle of syncytial embryos. However, cell cycle function of the enzyme is suggested by the mitotic defects exhibited by two Drosophila mutants, aar1 and twinsP, defective in the gene encoding the 55 kDa subunit. The reduced levels of the 55 kDa subunit correlate with the loss of protein phosphatase 2A-like, okadaic acid-sensitive phosphatase activity of brain extracts against caldesmon and histone H1 phosphorylated by p34cdc2/cyclin B kinase, but not against phosphorylase a. Thus the mitotic defects of aar1 and twinsP are likely to result from the lack of dephosphorylation of specific substrates by protein phosphatase 2A.

scholarly journals Loss of a Protein Phosphatase 2A Regulatory Subunit (Cdc55p) Elicits Improper Regulation of Swe1p Degradation

2000 ◽  
Vol 20 (21) ◽  
pp. 8143-8156 ◽  
Author(s):  
Haifeng Yang ◽  
Wei Jiang ◽  
Matthew Gentry ◽  
Richard L. Hallberg
Keyword(s):  
Phosphatase Activity ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Cell Types ◽  
Regulatory Subunit ◽  
Cyclin Dependent Kinase ◽  
Wild Type ◽  
Phosphatase 2A

ABSTRACT CDC55 encodes a Saccharomyces cerevisiaeprotein phosphatase 2A (PP2A) regulatory subunit.cdc55-null cells growing at low temperature exhibit a failure of cytokinesis and produce abnormally elongated buds, butcdc55-null cells producing the cyclin-dependent kinase Cdc28-Y19F, which is unable to be inhibited by Y19 phosphorylation, show a loss of the abnormal morphology. Furthermore,cdc55-null cells exhibit a hyperphosphorylation of Y19. For these reasons, we have examined in wild-type and cdc55-null cells the levels and activities of the kinase (Swe1p) and phosphatase (Mih1p) that normally regulate the extent of Cdc28 Y19 phosphorylation. We find that Mih1p levels are comparable in the two strains, and an estimate of the in vivo and in vitro phosphatase activity of this enzyme in the two cell types indicates no marked differences. By contrast, while Swe1p levels are similar in unsynchronized and S-phase-arrested wild-type and cdc55-null cells, Swe1 kinase is found at elevated levels in mitosis-arrestedcdc55-null cells. This excess Swe1p incdc55-null cells is the result of ectopic stabilization of this protein during G2 and M, thereby accounting for the accumulation of Swe1p in mitosis-arrested cells. We also present evidence indicating that, in cdc55-null cells, misregulated PP2A phosphatase activity is the cause of both the ectopic stabilization of Swe1p and the production of the morphologically abnormal phenotype.

scholarly journals Molecular genetic analysis of Rts1p, a B' regulatory subunit of Saccharomyces cerevisiae protein phosphatase 2A.

1997 ◽  
Vol 17 (6) ◽  
pp. 3242-3253 ◽  
Author(s):  
Y Shu ◽  
H Yang ◽  
E Hallberg ◽  
R Hallberg
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
High Temperatures ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Molecular Genetic Analysis ◽  
Regulatory Subunit ◽  
Temperature Sensitive ◽  
Checkpoint Control ◽  
Phosphatase 2A

The Saccharomyces cerevisiae gene RTS1 encodes a protein homologous to a variable B-type regulatory subunit of the mammalian heterotrimeric serine/threonine protein phosphatase 2A (PP2A). We present evidence showing that Rts1p assembles into similar heterotrimeric complexes in yeast. Strains in which RTS1 has been disrupted are temperature sensitive (ts) for growth, are hypersensitive to ethanol, are unable to grow with glycerol as their only carbon source, and accumulate at nonpermissive temperatures predominantly as large-budded cells with a 2N DNA content and a nondivided nucleus. This cell cycle arrest can be overcome and partial suppression of the ts phenotype of rts1-null cells occurs if the gene CLB2, encoding a Cdc28 kinase-associated B-type cyclin, is expressed on a high-copy-number plasmid. However, CLB2 overexpression has no suppressive effects on other aspects of the rts1-null phenotype. Expression of truncated forms of Rts1p can also partially suppress the ts phenotype and can fully suppress the inability of cells to grow on glycerol and the hypersensitivity of cells to ethanol. By contrast, the truncated forms do not suppress the accumulation of large-budded cells at high temperatures. Coexpression of truncated Rts1p and high levels of Clb2p fully suppresses the ts phenotype, indicating that the inhibition of growth of rts1-null cells at high temperatures is due to both stress-related and cell cycle-related defects. Genetic analyses show that the role played by Rts1p in PP2A regulation is distinctly different from that played by the other known variable B regulatory subunit, Cdc55p, a protein recently implicated in checkpoint control regulation.

scholarly journals Protein phosphatase 2A regulatory subunit B56α limits phosphatase activity in the heart

2015 ◽  
Vol 8 (386) ◽  
pp. ra72-ra72 ◽  
Author(s):  
Sean C. Little ◽  
Jerry Curran ◽  
Michael A. Makara ◽  
Crystal F. Kline ◽  
Hsiang-Ting Ho ◽  
...  
Keyword(s):  
Phosphatase Activity ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Regulatory Subunit ◽  
Phosphatase 2A

scholarly journals Localization of Saccharomyces cerevisiae Protein Phosphatase 2A Subunits throughout Mitotic Cell Cycle

2002 ◽  
Vol 13 (10) ◽  
pp. 3477-3492 ◽  
Author(s):  
Matthew S. Gentry ◽  
Richard L. Hallberg
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Protein Phosphatase ◽  
Fluorescent Protein ◽  
Protein Phosphatase 2A ◽  
Mitotic Cell ◽  
Regulatory Subunit ◽  
Regulatory Subunits ◽  
C Subunit ◽  
Phosphatase 2A

Protein phosphatase 2A (PP2A) regulates a broad spectrum of cellular processes. This enzyme is a collection of varied heterotrimeric complexes, each composed of a catalytic (C) and regulatory (B) subunit bound together by a structural (A) subunit. To understand the cell cycle dynamics of this enzyme population, we carried out quantitative and qualitative analyses of the PP2A subunits of Saccharomyces cerevisiae. We found the following: the level of each subunit remained constant throughout the cell cycle; there is at least 10 times more of one of the regulatory subunits (Rts1p) than the other (Cdc55p); Tpd3p, the structural subunit, is limiting for both catalytic and regulatory subunit binding. Using green fluorescent protein-tagged forms of each subunit, we monitored the sites of significant accumulation of each protein throughout the cell cycle. The two regulatory subunits displayed distinctly different dynamic localization patterns that overlap with the A and C subunits at the bud tip, kinetochore, bud neck, and nucleus. Using strains null for single subunit genes, we confirmed the hypothesis that regulatory subunits determine sites of PP2A accumulation. Although Rts1p and Tpd3p required heterotrimer formation to achieve normal localization, Cdc55p achieved its normal localization in the absence of either an A or C subunit.

Basidiomycete Fungal Gene Encoding a Regulatory Subunit A Homologue of Protein Phosphatase 2A

2000 ◽  
Vol 64 (2) ◽  
pp. 438-442 ◽  
Author(s):  
Takayuki ISHIZAKI ◽  
Hiroshi YOKOYAMA ◽  
Susumu KAJIWARA ◽  
Kazuo SHISHIDO
Keyword(s):  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Regulatory Subunit ◽  
Gene Encoding ◽  
Subunit A ◽  
Phosphatase 2A ◽  
Fungal Gene

The 55 kd regulatory subunit of Drosophila protein phosphatase 2A is required for anaphase

Cell ◽  
1993 ◽  
Vol 72 (4) ◽  
pp. 621-633 ◽  
Author(s):  
Regina E. Mayer-Jaekel ◽  
Hiroyuki Ohkura ◽  
Rui Gomes ◽  
Claudio E. Sunkel ◽  
Stefan Baumgartner ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Regulatory Subunit ◽  
Drosophila Protein ◽  
Phosphatase 2A

scholarly journals Molecular cloning, expression, and characterization of PTPA, a protein that activates the tyrosyl phosphatase activity of protein phosphatase 2A.

1994 ◽  
Vol 269 (22) ◽  
pp. 15668-15675 ◽  
Author(s):  
X. Cayla ◽  
C. Van Hoof ◽  
M. Bosch ◽  
E. Waelkens ◽  
J. Vandekerckhove ◽  
...  
Keyword(s):  
Molecular Cloning ◽  
Phosphatase Activity ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Phosphatase 2A

scholarly journals Structure and expression of a 72-kDa regulatory subunit of protein phosphatase 2A. Evidence for different size forms produced by alternative splicing

1993 ◽  
Vol 268 (20) ◽  
pp. 15267-15276
Author(s):  
P. Hendrix ◽  
R.E. Mayer-Jackel ◽  
P. Cron ◽  
J. Goris ◽  
J. Hofsteenge ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Regulatory Subunit ◽  
Phosphatase 2A
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