Document Detail

Sucrose-phosphate synthase is dephosphorylated by protein phosphatase 2A in spinach leaves. Evidence from the effects of okadaic acid and microcystin.
MedLine Citation:
PMID:  2171989     Owner:  NLM     Status:  MEDLINE    
Sucrose-phosphate synthase (SPS) purified from spinach leaves harvested in the dark, was activated by mammalian protein phosphatase 2A (PP2A). Activation of SPS in a fraction from darkened spinach leaves was largely prevented by either okadaic acid or microcystin-LR (specific inhibitors of PPI and PP2A), while inhibitor-2 (a PP1 inhibitor) or Mg2+ (essential for PP2C) were ineffective. In vivo, okadaic acid and microcystin-LR prevented the light-induced activation of SPS and decreased sucrose biosynthesis and CO2 fixation. It is concluded that PP2A is the major SPS phosphatase in spinach. This study is the first to employ microcystin-LR for modulating protein phosphorylation in vivo.
G Siegl; C MacKintosh; M Stitt
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  FEBS letters     Volume:  270     ISSN:  0014-5793     ISO Abbreviation:  FEBS Lett.     Publication Date:  1990 Sep 
Date Detail:
Created Date:  1990-12-10     Completed Date:  1990-12-10     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0155157     Medline TA:  FEBS Lett     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  198-202     Citation Subset:  IM    
Lehrstuhl für Pflanzenphysiologie, Universität Bayreuth, FRG.
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MeSH Terms
Enzyme Activation
Ethers, Cyclic / pharmacology
Glucosyltransferases / isolation & purification,  metabolism*
Marine Toxins / pharmacology
Okadaic Acid
Peptides, Cyclic / pharmacology
Phosphoprotein Phosphatases / physiology*
Phosphorylation / drug effects
Photosynthesis / physiology
Plants / enzymology*
Protein Phosphatase 2
Reg. No./Substance:
0/Ethers, Cyclic; 0/Marine Toxins; 0/Microcystins; 0/Peptides, Cyclic; 101043-37-2/cyanoginosin LR; 78111-17-8/Okadaic Acid; EC 2.4.1.-/Glucosyltransferases; EC synthase; EC Phosphatases; EC Phosphatase 2

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