Abstract
Sucrose synthase (SuSy) plays an important role in sucrose degradation and occurs both as a soluble and as a membrane-associated enzyme in higher plants. We show that membrane association can vary in vivo in response to gravistimulation, apparently involving SuSy dephosphorylation, and is a reversible process in vitro. Phosphorylation of SuSy has little effect on its activity but decreases its surface hydrophobicity as reported with the fluorescent probe bis-ANS. We postulate that phosphorylation of SuSy (and perhaps other membrane proteins) is involved in the release of the membrane-bound enzyme in part as a result of decreased surface hydrophobicity.
Publication types
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Adenosine Triphosphate / metabolism
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Anilino Naphthalenesulfonates / metabolism
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Blotting, Western
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Cyclic AMP-Dependent Protein Kinases / antagonists & inhibitors
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Cyclic AMP-Dependent Protein Kinases / metabolism
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Electrophoresis, Polyacrylamide Gel
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Enzyme Inhibitors / pharmacology
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Fluorescent Dyes / metabolism
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Glucosyltransferases / analysis
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Glucosyltransferases / metabolism*
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Gravitation
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Membrane Proteins / metabolism
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Phosphorylation
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Plant Proteins / metabolism
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Precipitin Tests
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Solubility
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Uridine Diphosphate Glucose / metabolism
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Zea mays / enzymology*
Substances
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Anilino Naphthalenesulfonates
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Enzyme Inhibitors
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Fluorescent Dyes
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Membrane Proteins
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Plant Proteins
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5,5'-bis(8-(phenylamino)-1-naphthalenesulfonate)
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Adenosine Triphosphate
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Glucosyltransferases
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sucrose synthase
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Cyclic AMP-Dependent Protein Kinases
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Uridine Diphosphate Glucose