72. イネGID1はジベレリンに対する核内受容体である

概要

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Gibberellins (GAs) regulate various developmental processes in plants. Recently we identified a rice Gibberellin Insensitive Dwarf1 (GID1) gene as for an ingredient of GA-insensitive dwarf mutants by positional cloning and detected the GA-binding activity in its recombinant protein (rGID1) prepared using an E. coli expressional system. We studied its ligand-selectivity using some GAs and their derivatives, which made it clear that the affinities to the rGID1 and their physiological activities are almost parallel and the highest affinity (K_d value) to it was shown to be around 10^<-7>M with GA_4. Three mutated rGID1s responsible for sever dwarf phenotype lost their GA-binding activity. We also checked the in vivo interaction between the GID1 and the negative regulator of GA-signaling, SLR1, using a yeast two-hybrid system. Their GA-dependent interaction was clearly confirmed. Taken together with other informations : (i) endogenous GA carrying physiologically active form accumulated 100-fold more in the mutants compared with that in a wild-type plant, (ii) overexpression of the gene leads to GA-hypersensitive, and (iii) the GID1-GFP was preferentially localized in nuclei, we concluded that the GID1 is a cytosolic GA receptor which localizes and functions in nuclei.
植物化学調節学会の論文
2005-10-13