Regulation of a plant plasma membrane sucrose transporter by phosphorylation.
The protein phosphatase inhibitor okadaic acid (OA) either provided directly to sugar beet (Beta vulgaris L.) leaf discs or infiltrated in the leaf blade rapidly inhibited sucrose uptake. Methyl okadaic acid, a biologically inactive analogue of OA, had only a marginal effect on uptake. OA inhibited proton-motive force-driven uptake of sucrose into plasma membrane vesicles, without affecting their proton permeability. OA did not significantly affect the amount of sucrose transporters present in the vesicles, as estimated by ELISA with specific antibodies. It is concluded that OA directly inhibits the activity of a H+-sucrose cotransporter of the plant plasma membrane, likely by maintaining it in a phosphorylated form.
Roblin
G
G
ERS CNRS 6099, Laboratoire de Physiologie et Biochimie Végétales, Poitiers, France.
Sakr
S
S
Bonmort
J
J
Delrot
S
S
D002731:4-Chloromercuribenzenesulfonate / Q000494:pharmacology; D000251:Adenosine Triphosphatases / Q000378:metabolism; D001692:Biological Transport; D002352:Carrier Proteins / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D019663:Chenopodiaceae / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D026901:Membrane Transport Proteins; D019319:Okadaic Acid / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism* / Q000493:pharmacokinetics
D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D026901:Membrane Transport Proteins; D010940:Plant Proteins; C078729:sucrose transport protein, plant; D019319:Okadaic Acid; D013395:Sucrose; D002731:4-Chloromercuribenzenesulfonate; D010749:Phosphoprotein Phosphatases; D000251:Adenosine Triphosphatases; C070990:vanadate-sensitive ATPase