Abstract
A rice proteinase REP-1 degrades seed storage proteins, and expression of the gene Rep1 is induced by gibberellin (GA). We found that two Myb transcription factors interact with a cis-element CARE in the Rep1 promoter, were encoded in the same gene and designated CTMyb1L (long type) and CTMyb1S (short type). CTMyb1S activates the Rep1 promoter with a GA responsible transcription factor OsGAMyb synergistically, but over-expression of CTMyb1L has no effect on Rep1 activation (Sutoh et al. 2007). In this study, bimolecular fluorescence complementation was carried out to analyze the complex formation between CTMyb1 and a DOF transcription factor RPBF involved in GA response and their localization. The complex between RPBF and CTMyb1S was detected in nucleus, although that between RPBF and CTMyb1L was found in cytoplasm. Co-expression of CTMyb1L and RPBF activated the Rep1 promoter, but CTMyb1S with RPBF did not. Taken together, it is probable that the RPBF CTMyb1L complex exports negative regulators outside nucleus, so that Rep1 expression is promoted.
