.alpha.- And .beta.-forms of the 65-kDa subunit of protein phosphatase 2A have a similar 39 amino acid repeating structure

Hemmings, BA; Adams-Pearson, C; Maurer, Fabienne; Müller, Peter; Goris, Jozef; Merlevede, Wilfried; Hofsteenge, Jan; Stone,

doi:10.1021/bi00465a002

Cited by 234 publications

(213 citation statements)

References 44 publications

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“…The supernatant of a bovine ROS preparation was subjected to a series of chromatographic procedures ( Figure 1A-C). Fractions were assayed for PP2A activity against phosphorylase a (9) and phosducin (2). The fractions with the highest phosducin activity, fractions 80-112 off the protamine-agarose column ( Figure 1A), 35-43 off the Ultrogel column ( Figure 1B), and 18-29 off the HTP column ( Figure 1C), were selected for subsequent purification steps.…”

Section: Resultsmentioning

confidence: 99%

“…For resolution of the PP2A trimer (ABC) and dimer (AC), peak HTP activity fractions were applied to a 5 to 20% sucrose gradient (D). Fractions were assayed for PP2A activity against phosphorylase a (9) and phosducin (2). The fractions with the highest phosducin dephosphorylation activity, fractions 80-112 off the protamineagarose, 35-43 off the Ultrogel, and 18-29 off the HTP column, were selected for subsequent purification steps.…”

Section: Pp2a Substrate Specificity Of the Trimer (Abc) And Dimer (Ac)mentioning

confidence: 99%

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Light-Driven Translocation of the Protein Phosphatase 2A Complex Regulates Light/Dark Dephosphorylation of Phosducin and Rhodopsin

et al. 2002

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In steps of protein purification of bovine retinal protein phosphatase 2A (PP2A), phosducin dephosphorylation activity peaks coelute with a PP2A enzyme complex, shown by peptide sequence analysis to contain a B′ subunit, B56epsilon. Other PP2A complexes with a slightly larger (56.5 kDa) B′ subunit (sequenced to be B56alpha) or with the BR regulatory subunit have no phosducin dephosphorylation activity. Upon exposure to light, a significant increase in the immunoreactive protein level of the A, C, and B56epsilon PP2A subunits is observed in the cytosolic fraction of mouse retina, the phosducin dephosphorylation of which occurs rapidly. During dark exposure, these subunits translocate to the membrane fraction where rhodopsin is slowly dephosphorylated. This PP2A redistribution occurs in less than 1.5 min and is dependent upon light and not upon an intrinsic circadian rhythm. Forty times more of the A subunit (∼20 ng/mouse retina) and 9 times more of the C subunit (∼4 ng/mouse retina) than of the B56epsilon subunit (∼0.45 ng/mouse retina) redistribute, which suggests that the predominant form of the PP2A enzyme complex on the membrane in the dark is a dimer, consisting of only A and C subunits. We observe that the dimer favors phosphorylated opsin as a substrate, while the trimer, particularly the enzyme complex with the B56epsilon subunit, greatly prefers phosphorylated phosducin, with an activity several hundred times those of other substrates that were tested. This light-driven PP2A translocation provides a potential mechanism for efficient dephosphorylation of two critical photoreceptor transduction proteins, cytosolic phosducin and membrane-bound rhodopsin, by the same enzyme.

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Section: Resultsmentioning

confidence: 99%

Section: Pp2a Substrate Specificity Of the Trimer (Abc) And Dimer (Ac)mentioning

confidence: 99%

Light-Driven Translocation of the Protein Phosphatase 2A Complex Regulates Light/Dark Dephosphorylation of Phosducin and Rhodopsin

et al. 2002

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“…HAtagged PP2A catalytic subunit was created by cloning human catalytic subunit (Stone et al, 1988) from nucleotide 58 ± 1022 in pMV-HAtag, introducing 19 additional amino acids between the HA tag and the ®rst methionine. HA-PR65 was created by cloning the human PR65 a cDNA (Hemmings et al, 1990), starting from amino acid 3, in pMV-HAtag. HA-PR72 was created by PCR using as 5' primer 5'-TCGCGTCGACGATGATGATCAAGGAAACATC-3' and T7 as 3' primer on the full length human PR72 cDNA in pBSK (Hendrix et al, 1993a).…”

Section: Methodsmentioning

confidence: 99%

“…For example, Protein Phosphatase 2A (PP2A) is a major intracellular serine/ threonine phosphatase that, apart from being involved in cell cycle regulation, plays a role in diverse cellular processes such as DNA-replication, intermediary metabolism, transcription and signal transduction (Hubbard and Cohen, 1993;Mumby and Walter, 1993;Virshup et al, 1993;Mayer-Jaekel and Hemmings, 1994). PP2A consists of a catalytic subunit (PP2Ac) (Cohen et al, 1990) and a structural 65 kDa subunit (PR65) (Hemmings et al, 1990). These two proteins form a core dimer (Hendrix et al, 1993b) to which various other regulatory`B' subunits associate.…”

Section: Introductionmentioning

confidence: 99%

Functional interaction between a novel protein phosphatase 2A regulatory subunit, PR59, and the retinoblastoma-related p107 protein

1999

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The proteins of the retinoblastoma family are potent inhibitors of cell cycle progression. It is well documented that their growth-inhibitory activity can be abolished by phosphorylation on serine and threonine residues by cyclin dependent kinases. In contrast, very little is known about the dephosphorylation of retinoblastoma-family proteins. We report here the isolation, by virtue of its ability to associate with p107, of a novel Protein Phosphatase 2A (PP2A) regulatory subunit, named PR59. PR59 shares sequence homology with a known regulatory subunit of PP2A, PR72, but di ers from PR72 in its expression pattern and its functional properties. We show that PR59 co-immunoprecipitates with the PP2A catalytic subunit, indicating that PR59 is a genuine component of PP2A holo-enzymes. In vivo, PR59 associates speci®cally with p107, but not with pRb. Elevated expression of PR59 results in dephosphorylation of p107, but not of pRb, and inhibits cell proliferation by causing cells to accumulate in G1. These data support a model in which the distinct PP2A regulatory subunits act to target the PP2A catalytic subunit to speci®c substrates and suggest a role for PP2A in regulation of p107.

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“…The regulatory A subunit has been identified in cells of diverse origin. Two isoforms of the A subunits have been characterized in mammalian cells (15) and one in Drosophila (16). In S. cerevisiae, the TPD3 gene encodes a homolog of the mammalian subunit (17).…”

mentioning

confidence: 99%

Saccharomyces cerevisiae Homologs of Mammalian B and B′ Subunits of Protein Phosphatase 2A Direct the Enzyme to Distinct Cellular Functions

Zhao

Boguslawski

Zitomer

et al. 1997

Journal of Biological Chemistry

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Protein phosphatase 2A (PP2A) is a major cellular serine/threonine protein phosphatase, present in the cell in a variety of heterotrimeric forms that differ in their associated regulatory B-subunit. Cloning of the mammalian B subunit has allowed the identification of a highly homologous Saccharomyces cerevisiae gene, RTS1. Disruption of the gene results in a temperaturesensitive growth defect that can be suppressed by expression of rabbit B ␣ or B ␥ isoforms. The B ␣ subunit is much more effective in restoring normal growth at 37°C than B ␥. Immunoprecipitated Rts1p was found associated with type 2A-specific protein phosphatase activity that is sensitive to 2 nM okadaic acid, but not to 100 nM phosphatase inhibitor-2, and to be phosphorylated in vivo. However, overexpression of RTS1 was unable to suppress the cold sensitivity, defective cytokinesis, and abnormal cell morphology resulting from defects in the CDC55 gene, which encodes the yeast homolog of a different B subunit of another form of 2A phosphatase, PP2A 1 . These results indicate that Rts1p is a yeast homolog of the mammalian B subunit and that the various regulatory B-subunits of PP2A are not functionally redundant but direct the enzyme to distinct cellular functions.

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.alpha.- And .beta.-forms of the 65-kDa subunit of protein phosphatase 2A have a similar 39 amino acid repeating structure

Cited by 234 publications

References 44 publications

Light-Driven Translocation of the Protein Phosphatase 2A Complex Regulates Light/Dark Dephosphorylation of Phosducin and Rhodopsin

Light-Driven Translocation of the Protein Phosphatase 2A Complex Regulates Light/Dark Dephosphorylation of Phosducin and Rhodopsin

Functional interaction between a novel protein phosphatase 2A regulatory subunit, PR59, and the retinoblastoma-related p107 protein

Saccharomyces cerevisiae Homologs of Mammalian B and B′ Subunits of Protein Phosphatase 2A Direct the Enzyme to Distinct Cellular Functions

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