Ca2+-dependent protein kinase from alfalfa (Medicago varia): Partial purification and autophosphorylation

László Bögre, Zoltán Oláh, Dénes Dudits

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31 Citations (Scopus)


A calcium-dependent protein kinase (CDPK) was purified to 1400-fold from the soluble fraction of alfalfa (Medicago varia) cells by ammonium sulfate fractionation, Sephacryl-300, DEAE-Sephacel, Phenyl-Sepharose and Hydroxylapatite column chromatography. The enzyme is mainly monomeric. During the course of the purification steps a 50 kDa phosphoprotein doublet and a 56 kDa phosphoprotein copurified with the CDPK activity. Mobility shift of these proteins have been shown by SDS PAGE in Ca2+ free conditions. Tests on enzyme activity after separation by native gel electrophoresis revealed two protein kinase activities in our enzyme preparation and the phosphorylation of the 50 kDa and 56 kDa proteins. We suggest that these proteins are the autophosphorylated forms of calcium dependent protein kinases. Preincubation of the CDPK in ATP resulted in a marked increase in enzyme activity, but did not alter the Ca2+ sensitivity of the protein kinase.

Original languageEnglish
Pages (from-to)135-144
Number of pages10
JournalPlant Science
Issue number2
Publication statusPublished - 1988


ASJC Scopus subject areas

  • Genetics
  • Agronomy and Crop Science
  • Plant Science

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