Abstract
DELLA proteins, which are a subgroup of GRAS proteins, are key factors of gibberellin (GA) signaling. Our previous studies revealed that, in rice cells, DELLA protein SLR1 functions as a repressor for GA action and is degraded GA-dependently by ubiquitin-proteasome system through the SCFGID2 function. However, it is unclear how the GA signal is transduced to SLR1 from bioactive GA molecular. Recently, we succeeded to identify a GA receptor, which has a similar primary structure to that of hormone sensitive lipase and is localized in nucleus. Interestingly, the yeast two-hybrid assay revealed that the interaction between GID1 and SLR1 occurs as a GA dependent manner. Thus we speculate that the complex composed by GID1, SLR1, and GA may recruit an F-box protein, GID2, to initiate the degradation of SLR1. To evaluate this, we have performed some biochemical experiments such as yeast three hybrid assay and pull-down assay in vitro.
