Sucrose‐phosphate synthase is dephosphorylated by protein phosphatase 2A in spinach leaves

FEBS Letters

Siegl, Gabriele²  MacKintosh, Carol¹  Stitt, Mark² 

[1] MRC Protein Phosphorylation Group. Department of Biochemistry, University of Dundee, Dundee DD1 4HN, UK;Lehrstuhlfür Pflanzenphysiologie, Universität Bayreuth, 8580 Bayreuth, FRG

关键词: Microcystin-LR;    Okadaic acid;    Protein phosphatase;    Photosynthesis;    Sucrose-phosphate synthase;    SPS;    sucrose-phosphate synthase;    Fru6P;    fructose 6-phosphate;    Glc6P;    glucose 6-phosphate;    UDPGIc;    uridine 5-diphosphoglucose;    Hepes;    4-(2-hydroxyethyl)-1-piperazineethanesulphonic acid;    Pi;    inorganic phosphate;    PP;    protein phosphatase;   

DOI  :  10.1016/0014-5793(90)81267-R

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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 PP1 and PP2A), while inhibitor-2 (a PP1 inhibitor) or Mg²⁺ (essential for PP2C) were ineffective. In vivo, okadaic add 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.

【 授权许可】

Unknown