scholarly journals Okadaic acid mimics the action of insulin in stimulating protein kinase activity in isolated adipocytes. The role of protein phosphatase 2a in attenuation of the signal.

1990 ◽  
Vol 265 (27) ◽  
pp. 16571-16580 ◽  
Author(s):  
T A Haystead ◽  
J E Weiel ◽  
D W Litchfield ◽  
Y Tsukitani ◽  
E H Fischer ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Kinase Activity ◽  
Protein Phosphatase 2A ◽  
Protein Kinase Activity ◽  
Phosphatase 2A ◽  
Isolated Adipocytes

scholarly journals A tightly associated serine/threonine protein kinase regulates phosphoinositide 3-kinase activity.

1993 ◽  
Vol 13 (3) ◽  
pp. 1657-1665 ◽  
Author(s):  
C L Carpenter ◽  
K R Auger ◽  
B C Duckworth ◽  
W M Hou ◽  
B Schaffhausen ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Phosphatase ◽  
Kinase Activity ◽  
Protein Phosphatase 2A ◽  
T Antigen ◽  
Serine Kinase ◽  
Phosphatase 2A ◽  
Phosphoinositide 3 Kinase

We identified a serine/threonine protein kinase that is associated with and phosphorylates phosphoinositide 3-kinase (PtdIns 3-kinase). The serine kinase phosphorylates both the 85- and 110-kDa subunits of PtdIns 3-kinase and purifies with it from rat liver and immunoprecipitates with antibodies raised to the 85-kDa subunit. Tryptic phosphopeptide maps indicate that p85 from polyomavirus middle T-transformed cells is phosphorylated in vivo at three sites phosphorylated in vitro by the associated serine kinase. The 85-kDa subunit of PtdIns 3-kinase is phosphorylated in vitro on serine at a stoichiometry of approximately 1 mol of phosphate per mol of p85. This phosphorylation results in a three- to sevenfold decrease in PtdIns 3-kinase activity. Dephosphorylation with protein phosphatase 2A reverses the inhibition. This suggests that the association of protein phosphatase 2A with middle T antigen may function to activate PtdIns 3-kinase.

scholarly journals Acute regulation of renal Na+/H+ exchanger NHE3 by dopamine: role of protein phosphatase 2A

2010 ◽  
Vol 298 (5) ◽  
pp. F1205-F1213 ◽  
Author(s):  
I. Alexandru Bobulescu ◽  
Henry Quiñones ◽  
Serge M. Gisler ◽  
Francesca Di Sole ◽  
Ming-Chang Hu ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Simian Virus 40 ◽  
Receptor Activation ◽  
T Antigen ◽  
Phosphatase 2A

Nephrogenic dopamine is a potent natriuretic paracrine/autocrine hormone that is central for mammalian sodium homeostasis. In the renal proximal tubule, dopamine induces natriuresis partly via inhibition of the sodium/proton exchanger NHE3. The signal transduction pathways and mechanisms by which dopamine inhibits NHE3 are complex and incompletely understood. This manuscript describes the role of the serine/threonine protein phosphatase 2A (PP2A) in the regulation of NHE3 by dopamine. The PP2A regulatory subunit B56δ (coded by the Ppp2r5d gene) directly associates with more than one region of the carboxy-terminal hydrophilic putative cytoplasmic domain of NHE3 (NHE3-cyto), as demonstrated by yeast-two-hybrid, coimmunoprecipitation, blot overlay, and in vitro pull-down assays. Phosphorylated NHE3-cyto is a substrate for purified PP2A in an in vitro dephosphorylation reaction. In cultured renal cells, inhibition of PP2A by either okadaic acid or by overexpression of the simian virus 40 (SV40) small T antigen blocks the ability of dopamine to inhibit NHE3 activity and to reduce surface NHE3 protein. Dopamine-induced NHE3 redistribution is also blocked by okadaic acid ex vivo in rat kidney cortical slices. These studies demonstrate that PP2A is an integral and critical participant in the signal transduction pathway between dopamine receptor activation and NHE3 inhibition.

Protein phosphatase 2A binds to the cytoplasmic tail of carboxypeptidase D and regulates post-trans-Golgi network trafficking

2001 ◽  
Vol 114 (2) ◽  
pp. 311-322
Author(s):  
O. Varlamov ◽  
E. Kalinina ◽  
F.Y. Che ◽  
L.D. Fricker
Keyword(s):  
Protein Kinase ◽  
Cell Surface ◽  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Cytoplasmic Tail ◽  
Trans Golgi Network ◽  
Phosphatase 2A ◽  
Carboxypeptidase D ◽  
Golgi Network

Carboxypeptidase D (CPD) is a transmembrane protein that processes proteins in the trans-Golgi network (TGN). A 20-residue region within the cytoplasmic tail of CPD binds protein phosphatase 2A (PP2A). PP2A also binds to the cytoplasmic tails of other secretory pathway proteins: peptidylglycine-(amino)-amidating mono-oxygenase, the cation-independent mannose-6-phosphate receptor and TGN38. The CPD tail is phosphorylated on Thr residues in the AtT-20 cell line. The CPD tail can also be phosphorylated by purified protein kinase A, protein kinase C and casein kinase II. Both the in vitro and the in vivo phosphorylated CPD tail can be dephosphorylated by purified PP2A. The binding of CPD tail peptide to PP2A does not influence phosphatase activity. The rate of transport of CPD from the TGN to the cell surface of AtT-20 cells is decreased 45% by okadaic acid, a PP2A inhibitor. Microinjection of the CPD tail into AtT-20 cells inhibits the transition of CPD from endosomal compartments to the TGN. However, okadaic acid does not affect the rate of budding of CPD from the TGN into nascent vesicles or the rate of uptake from the cell surface into endosomal compartments. These results are consistent with the model that PP2A is involved in the trafficking of proteins between a TGN recycling loop and a cell-surface recycling loop, but is not involved in the individual recycling loops.

Inhibition of 5‐HT1Areceptor‐dependent cell survival by cAMP/protein kinase A: Role of protein phosphatase 2A and Bax

2008 ◽  
Vol 86 (10) ◽  
pp. 2326-2338 ◽  
Author(s):  
Shu‐chi Hsiung ◽  
Adrianne Tin ◽  
Hadassah Tamir ◽  
Thomas F. Franke ◽  
Kuo‐peing Liu
Keyword(s):  
Protein Kinase ◽  
Cell Survival ◽  
Protein Kinase A ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Phosphatase 2A ◽  
Dependent Cell ◽  
Kinase A

A tightly associated serine/threonine protein kinase regulates phosphoinositide 3-kinase activity

1993 ◽  
Vol 13 (3) ◽  
pp. 1657-1665
Author(s):  
C L Carpenter ◽  
K R Auger ◽  
B C Duckworth ◽  
W M Hou ◽  
B Schaffhausen ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Phosphatase ◽  
Kinase Activity ◽  
Protein Phosphatase 2A ◽  
T Antigen ◽  
Serine Kinase ◽  
Phosphatase 2A ◽  
Phosphoinositide 3 Kinase

We identified a serine/threonine protein kinase that is associated with and phosphorylates phosphoinositide 3-kinase (PtdIns 3-kinase). The serine kinase phosphorylates both the 85- and 110-kDa subunits of PtdIns 3-kinase and purifies with it from rat liver and immunoprecipitates with antibodies raised to the 85-kDa subunit. Tryptic phosphopeptide maps indicate that p85 from polyomavirus middle T-transformed cells is phosphorylated in vivo at three sites phosphorylated in vitro by the associated serine kinase. The 85-kDa subunit of PtdIns 3-kinase is phosphorylated in vitro on serine at a stoichiometry of approximately 1 mol of phosphate per mol of p85. This phosphorylation results in a three- to sevenfold decrease in PtdIns 3-kinase activity. Dephosphorylation with protein phosphatase 2A reverses the inhibition. This suggests that the association of protein phosphatase 2A with middle T antigen may function to activate PtdIns 3-kinase.

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