Membrane-associated protein kinase activities in the developing mesocarp of grape berry.
Fruit development is a process involving various signals and gene expression. Protein phosphorylation catalyzed 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, we characterised the calcium-dependent and calmodulin-independent protein kinase (CDPK) activity and the myelin basic protein (MBP)-phosphoralating activity that could be due to a mitogen-activated protein kinase (MAPK)-like activity in the developing mesocarp of grape berry. The CDPK activity was shown to be predominantly localised in the plasma membrane, while the MAPK-like activity was predominantly associated with endomembranes. The assays of bivalent cation requirement showed that Mn2+ could to a certain extent replace Mg2+ in the incubation system for the protein kinase activities. Both CDPK and MAPK-like activities were resistant to heat treatment. The activities of the two enzymes were fruit developmental stage-specific with the highest activities of both enzymes in the lag growth phase before the ripening stage, suggesting strongly the important roles of the detected CDPK and MAPK-like activities in the fruit development.
China State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, 100094 Beijing, People's Republic of China.
Yuan-Yue
YY
Shen
Chang-Qing
CQ
Duan
Xiao-E
XE
Liang
Da-Peng
DP
Zhang
D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D013347:Subcellular Fractions / Q000201:enzymology / Q000378:metabolism; D027843:Vitis / Q000201:enzymology / Q000254:growth & development*
D011494:Protein Kinases; D002118:Calcium