Planta

, Volume 177, Issue 1, pp 116–120

Regulation of sucrose-phosphate-synthase activity in spinach leaves by protein level and covalent modification

  • Joan L. Walker
  • Steven C. Huber
Article

DOI: 10.1007/BF00392161

Cite this article as:
Walker, J.L. & Huber, S.C. Planta (1989) 177: 116. doi:10.1007/BF00392161

Abstract

A dot-blot technique was developed using monoclonal antibodies to measure, rapidly and accurately, the amount of sucrose-phosphate synthase (SPS; EC 2.4.1.14) protein present in a crude extract from spinach (Spinacia oleracea L. cv. Dark Green Bloomsdale) leaves; this was compared with SPS activity in this material. During leaf development, increased SPS activity followed closely the increase in enzyme-protein level, indicating denovo synthesis or altered turn-over rates for SPS. In contrast, activation of SPS by illumination of leaves or by mannose treatment of leaf discs in the dark (M. Stitt et al. Planta 174, 217–230) occurred without a significant change in the level of enzyme protein. Since conditions which altered SPS activity did not affect immunoprecipitation or mobility of the 120-kilodalton (kDa) subunit of the enzyme during denaturing gel electrophoresis, some form of protein modification other than proteolysis must be involved. Overall, the results indicate that regulation of SPS activity can involve changes in the level of enzyme protein and-or covalent modification.

Key words

Leaf development Light (enzyme activation) Photosynthate partitioning Spinacia (sucrose-phosphate synthase) Sucrose-phosphate synthase 

Abbreviations

kDa

kilodalton

SDS-PAGE

sodium dodecylsulfate polyacrylamide gel electrophoresis

SPS

sucrosephosphate synthase

Copyright information

© Springer-Verlag 1989

Authors and Affiliations

  • Joan L. Walker
    • 1
    • 2
    • 3
  • Steven C. Huber
    • 1
    • 2
    • 3
  1. 1.U.S. Department of Agriculture, Agricultural Research ServiceNorth Carolina State UniversityRaleighUSA
  2. 2.Department of Crop ScienceNorth Carolina State UniversityRaleighUSA
  3. 3.Department of BotanyNorth Carolina State UniversityRaleighUSA

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