Distribution of protein phosphatases type 1 and 2A in RINm5F cells.
In the insulin producing cell line RINm5F distribution of serine/threonine specific protein phosphatases type 1 (PP1) and 2A (PP2A) was studied. Using different agents which inhibit or stimulate PP1 and PP2A we found that in membrane and nuclear fractions phosphatase activity was inhibited by okadaic acid (OA), protamine, heparin, and inhibitor-2 in a concentration-dependent manner. C2-ceramide had no effect. In the cytosolic fraction the inhibitory effect of okadaic acid was tenfold higher. Protamine stimulated phosphatase activity at low concentrations and became inhibitory at higher concentrations. Inhibitor-2 and heparin caused a decrease in phosphatase activity whereas C2-ceramide led to a slight activation. The data suggest that in membrane and nuclear fractions of RINmSF cells predominantly PP1 is present, whereas in the cytosol PP1 as well as PP2A can be detected.
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Institute of Pharmaceutical Sciences, Department of Pharmacology, University of Tübingen, Germany.
Heurich
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Drews
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Ammon
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D000818:Animals; D015415:Biomarkers / Q000737:chemistry; D002458:Cell Fractionation; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006493:Heparin / Q000494:pharmacology; D056488:Histone Chaperones; D007515:Islets of Langerhans / Q000201:enzymology*; D019319:Okadaic Acid / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010762:Phosphorylase a / Q000378:metabolism; D011479:Protamines / Q000494:pharmacology; D011506:Proteins / Q000494:pharmacology; D051381:Rats; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D014157:Transcription Factors; D014407:Tumor Cells, Cultured
D015415:Biomarkers; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D056488:Histone Chaperones; C064769:N-acetylsphingosine; D010750:Phosphoproteins; D011479:Protamines; D011506:Proteins; C513473:SET protein, human; D014157:Transcription Factors; D019319:Okadaic Acid; D006493:Heparin; D010762:Phosphorylase a; D010749:Phosphoprotein Phosphatases; D013110:Sphingosine