scholarly journals Fructose-2,6-bisphosphatase and 6-phosphofructo-2-kinase are separable in yeast

1987 ◽  
Vol 246 (3) ◽  
pp. 755-759 ◽  
Author(s):  
M Kretschmer ◽  
W Schellenberger ◽  
A Otto ◽  
R Kessler ◽  
E Hofmann
Keyword(s):  
Alkaline Phosphatase ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Dependent Protein Kinase ◽  
Km Value ◽  
Phosphatase 2A ◽  
Dependent Protein

Fructose-2,6-bisphosphatase was purified from yeast and separated from 6-phosphofructo-2-kinase and alkaline phosphatase. The enzyme released Pi from the 2-position of fructose 2,6-bisphosphate and formed fructose 6-phosphate in stoichiometric amounts. The enzyme displays hyperbolic kinetics towards fructose 2,6-bisphosphate, with a Km value of 0.3 microM. It is strongly inhibited by fructose 6-phosphate. The inhibition is counteracted by L-glycerol 3-phosphate. Phosphorylation of the enzyme by cyclic-AMP-dependent protein kinase causes inactivation, which is reversible by the action of protein phosphatase 2A.

Regulation of an epithelial chloride channel by direct phosphorylation and dephosphorylation

1992 ◽  
Vol 263 (1) ◽  
pp. C172-C175 ◽  
Author(s):  
A. L. Finn ◽  
M. L. Gaido ◽  
M. Dillard ◽  
D. L. Brautigan
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Lipid Bilayers ◽  
Okadaic Acid ◽  
Specific Antibody ◽  
Chloride Channel ◽  
Protein Phosphatase ◽  
Dependent Protein Kinase ◽  
Phosphatase 2A ◽  
Dependent Protein

A native chloride channel in Necturus gallbladder epithelial cells is opened by a theophylline-induced rise in cellular cyclic AMP and is closed by removal of theophylline or by addition of specific antibody; however, it does not close if okadaic acid, an inhibitor of protein phosphatases 1 and 2A, is added. The purified channel reconstituted into lipid bilayers closes upon the addition of protein phosphatase 2A and is reopened by the addition of Mg-ATP and the catalytic subunit of cyclic AMP-dependent protein kinase. These results indicate that the channel protein is purified in a phosphorylated state and that its functional characteristics are at least partly controlled by direct phosphorylation and dephosphorylation.

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