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Calcium-regulated in vivo protein phosphorylation in Zea mays L. root tipsCalcium dependent protein phosphorylation was studied in corn (Zea mays L.) root tips. Prior to in vivo protein phosphorylation experiments, the effect of calcium, ethyleneglycol-bis-(beta-aminoethyl ether)-N-N' -tetraacetic acid (EGTA) and calcium ionophore (A-23187) on phosphorus uptake was studied. Calcium increased phosphorus uptake, whereas EGTA and A-23187 decreased it. Consequently, phosphorus concentration in the media was adjusted so as to attain similar uptake in different treatments. Phosphoproteins were analyzed by two-dimensional gel electrophoresis. Distinct changes in phosphorylation were observed following altered calcium levels. Calcium depletion in root tips with EGTA and A-23187 decreased protein phosphorylation. However, replenishment of calcium following EGTA and ionophore pretreatment enhanced phosphorylation of proteins. Preloading of the root tips with 32P in the presence of EGTA and A-23187 followed by a ten minute calcium treatment, resulted in increased phosphorylation indicating the involvement of calcium, calcium and calmodulin-dependent kinases. Calmodulin antagonist W-7 was effective in inhibiting calcium-promoted phosphorylation. These studies suggest a physiological role for calcium-dependent phosphorylation in calcium-mediated processes in plants.
Document ID
20040089871
Document Type
Reprint (Version printed in journal)
Authors
Raghothama, K. G. (Washington State University Pullman 99164-6414, United States)
Reddy, A. S.
Friedmann, M.
Poovaiah, B. W.
Date Acquired
August 21, 2013
Publication Date
January 1, 1987
Publication Information
Publication: Plant physiology
Volume: 83
ISSN: 0032-0889
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: DCB-8502215
CONTRACT_GRANT: NAG10-0032
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Plant Biology
NASA Program Space Biology
Non-NASA Center
NASA Discipline Number 40-30