The role of extracellular calmodulin in regulating expression of rbcS in darkness was examined. A suspension-cultured cell line was generated from the transgenic rbcS-GUS tobacco. It was demonstrated that purified cal...The role of extracellular calmodulin in regulating expression of rbcS in darkness was examined. A suspension-cultured cell line was generated from the transgenic rbcS-GUS tobacco. It was demonstrated that purified calmodulin added to the media enhanced rbcS-GUS expression. The time course of expression of rbcS-GUS and that of the secretion of calmodulin in the suspended transgenic tobacco cells in darkness were very similar. Both showed initial increase followed by decline with maximum calmodulin secretion preceding maximum GUS expression. The addition of membrane-impermeable calmodulin antagonist W7-agarose inhibited the expression of rbcS-GUS in darkness, but this inhibitory effect was completely reversed by adding exogenous purified calmodulin. These results provide the first evidence that extracellular calmodulin accelerates rbcS gene expression.展开更多
文摘The role of extracellular calmodulin in regulating expression of rbcS in darkness was examined. A suspension-cultured cell line was generated from the transgenic rbcS-GUS tobacco. It was demonstrated that purified calmodulin added to the media enhanced rbcS-GUS expression. The time course of expression of rbcS-GUS and that of the secretion of calmodulin in the suspended transgenic tobacco cells in darkness were very similar. Both showed initial increase followed by decline with maximum calmodulin secretion preceding maximum GUS expression. The addition of membrane-impermeable calmodulin antagonist W7-agarose inhibited the expression of rbcS-GUS in darkness, but this inhibitory effect was completely reversed by adding exogenous purified calmodulin. These results provide the first evidence that extracellular calmodulin accelerates rbcS gene expression.
