Calcium-dependent protein kinase from apple fruit membranes is calmodulin-independent but has calmodulin-like properties |
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Authors: | N H Battey M A Venis |
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Institution: | (1) Institute of Horticultural Research, East Malling, ME19 6BJ Maidstone, Kent, UK;(2) Present address: Department of Horticulture, University of Reading, Whiteknights, PO Box 221, RG6 2AS Reading, UK |
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Abstract: | Crude Ca2+-activated protein kinase from membranes of apple (Malus domestica L. Borkh., Cox's Orange Pippin) fruit can be partially purified to yield a Ca2+-dependent protein kinase whose activity is apparently not regulated by calmodulin. The autophosphorylating catalytic subunit of this protein kinase shows a Ca2+-dependent mobility shift of approx. 10 kilodaltons (kDa) on sodium dodecyl sulphate-polyacrylamide gel electrophoresis; in the absence of added Ca2+ or ethylene glycol-bis( -aminoethyl ether)-N,N,N ,N -tetraacetic acid (EGTA) its apparent molecular mass is approx. 50 kDa. The Ca2+-dependent protein kinase is inhibited by the calmodulin antagonists N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide and trifluoperazine with IC50 values of approx. 45 M and 15 M, respectively. These similarities between the protein kinase and calmodulin indicate that the kinase may be a calmodulin-like protein.Abbreviations DEAE
diethylaminoethyl
- EGTA
ethylene glycol-bis( -aminoethyl ether)-N,N,N ,N -tetraacetic acid
- Hepes
4-(-2-hydroxyethyl)-1-piperazineethanesulphonic acid
- kDa
kilodalton
- PAGE
polyacrylamide gel electrophoresis
- SDS
sodium dodecyl sulphate
- W7
N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide
- W5
N-(6-aminohexyl)-naphthalenesulphonamide |
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Keywords: | Calcium Calmodulin Malus (protein kinase) Protein kinase |
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