PLANT PHYSIOLOGY , Vol 108, Issue 1 219-225, Copyright © 1995 by American Society of Plant Biologists
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BIOCHEMISTRY AND ENZYMOLOGY |
Antibodies That Distinguish between the Serine-158 Phospho- and Dephospho-Form of Spinach Leaf Sucrose-Phosphate Synthase
H. Weiner
Botanisches Institut der Universitat Heidelberg, Im Neuenheimer Feld 360, 69120 Heidelberg, Germany
Serum antibodies were raised against a synthetic peptide corresponding to
the amino acid sequence surrounding the major inactivating phosphorylation
site (serine-158) of spinach (Spinacia oleracea) leaf sucrose-phosphate
synthase (SPS). The anti-peptide antibodies precipitated highly activated
SPS preferentially to ATP-inactivated SPS and interacted only weakly with
the sodium dodecyl sulfate-denatured enzyme bound to a membrane. The
antibodies blocked phosphorylation but not dephosphorylation of SPS. Highly
activated SPS was not entirely dephosphorylated and ATP-inactivated SPS was
not completely phosphorylated on serine-158, as indicated by the
sensitivities of immunopurified serine-158 phospho- and dephospho-SPS to
inhibition by inorganic phosphate. The anti-peptide antibodies can be used
to detect changes in the phosphorylation state of serine-158, and they are
useful to purify and characterize distinct kinetic forms of SPS.