The phosphorylation site of Ca2+-dependent protein kinase from alfalfa

Zoltan Olah, Laszlo Bogre, Csaba Lehel, Anna Farago, Janos Seprodi, Denes Dudits

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21 Citations (Scopus)


A 50 kDa, calcium-dependent protein kinase (CDPK) was purified about 1000-fold from cultured cells of alfalfa (Medicago varia) on the basis of its histone H1 phosphorylation activity. The major polypeptide from bovine histone H1 phosphorylated by either animal protein kinase C (PK-C) or by the alfalfa CDPK gave an identical phosphopeptide pattern. The phosphoamino acid determination showed phosphorylation of serine residues in histone H1 by the plant enzyme. Histone-related oligopeptides known to be substrates for animal histone kinases also served as substrates for the alfalfa kinase. Both of the studied peptides (GKKRKRSRKA; AAASFKAKK) inhibited phosphorylation of H1 histones by bovine and alfalfa kinases. The results of competition studies with the nonapeptide (AAASFKAKK), which is a PK-C specific substrate, suggest common features in target recognition between the plant Ca2+-dependent kinase and animal protein kinase C. We also propose that synthetic peptides like AAASFKAKK can be used as a tool to study substrates of plant kinases in crude cell extracts.

Original languageEnglish
Pages (from-to)453-461
Number of pages9
JournalPlant molecular biology
Issue number4
Publication statusPublished - Apr 1 1989



  • Ca-dependent protein kinase (CDPK)
  • alfalfa
  • oligopeptide substrate
  • peptide competition
  • protein kinase C
  • substrate specificity

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Genetics
  • Plant Science

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