| 11092909 |
Yang G, Komatsu S: Involvement of calcium-dependent protein kinase in rice (Oryza sativa L.) lamina inclination caused by brassinolide. Plant Cell Physiol. 2000 Nov;41(11):1243-50.
Promotive effect of brassinolide (BL) on green lamina inclination was concentration-dependent when excised rice (Oryza sativa L.) lamina was floated on BL solution under continuous light conditions. Protein kinase inhibitor staurosporine and Ca2+ channel blocker LaCl3 could completely, while Ca2+ chelator EGTA could partially inhibit the lamina inclination caused by BL. Two protein kinases with apparent molecular masses of 45 and 54 kDa were detected using an in-gel kinase assay with histone III-S as a substrate. In particular, the changes in 45 kDa protein kinase activity correlated with lamina inclination caused by BL. The 45 kDa kinase activity was inhibited by Ca2+ chelator EGTA, protein kinase inhibitor, staurosporine and calmodulin antagonist W-7. Therefore, this 45 kDa protein kinase was identified as a Ca2+ -dependent protein kinase (CDPK). Patterns of 2-dimensional PAGE after in vitro phosphorylation of crude extracts showed that the phosphorylation of 56 and 41 kDa proteins, which was Ca2+ -dependent, was strongly increased by BL treatment. These results suggested that CDPK and Ca2+ -dependent protein phosphorylation are involved in BL-induced rice lamina inclination. |
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