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Membrane‐associated protein kinase activities in developing apple fruit
Author(s) -
Duan ChangQing,
Shen YuanYue,
Liang XiaoE,
Zhang DaPeng
Publication year - 2003
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2003.00103.x
Subject(s) - kinase , protein kinase a , phosphatidylserine , microbiology and biotechnology , mapk/erk pathway , phosphorylation , biology , myelin basic protein , protein phosphorylation , substrate level phosphorylation , biochemistry , membrane , myelin , phospholipid , neuroscience , central nervous system
Fruit development is a process involving various signals and gene expression. Protein phosphorylation catalysed by protein kinases is known to play a key role in eukaryotic cell signalling and so may be involved in the regulation of fruit development. Using the method of exogenous substrate phosphorylation, the activity of calcium‐dependent and calmodulin‐independent protein kinase (CDPK) that was stimulated by phosphatidylserine, and the myelin basic protein (MBP)‐phosphorylating activity that could be due to a calcium‐independent mitogen‐activated protein kinase‐like (MAPK‐like) activity in the developing apple fruits were identified. The CDPK activity was shown to be predominantly localized in the plasma membrane, whereas in the presence of phosphatidylserine, the high activity of CDPK was detected in both plasma membrane and endomembranes. The MAPK‐like activity was predominantly associated with endomembranes. The assays of bivalent cation requirement showed that Mn 2+ could replace Mg 2+ in the incubation system for the protein kinase activities and stimulate CDPK activity more than Mg 2+ . Heat treatment abolished CDPK but stimulated MAPK‐like activity. The activities of the phosphatidylserine‐stimulated CDPK and of the MAPK‐like were fruit developmental stage‐specific with higher activities of both enzymes in the early and middle developmental stages in comparison with the late developmental stage. These data suggest that the detected protein kinases may play an important role in the fruit development.