Abstract
The 26S proteasome is an active proteolytic complex consisting of a 20S core protease capped at ends by a 19S regulatory particle. The 19S is made up of six ATPases (RPT) and, at least, 11 non-ATPase subunits. In Arabidopsis genome, the RPT2 subunits are encoded by two genes, AtRPT2a and AtRPT2b.
We found that rice RPT2a is expressed in the sugar treated embryos by microarray analysis. In Arabidopsis, T-DNA inserted knockout mutant of AtRPT2a (rpt2a) showed hyper-response to sugars and the AtRPT2a expression was largely enhanced by sucrose application, while the AtRPT2b did not. The rpt2a displays abnormally root apical meristem and leaf shapes, since halted root mutant is the same allele of the rpt2a (Ueda et al. 2004 Development 131: 2101-2111), indicating that sugar signaling which is partially associated with plant development is mediated through proteasome-dependent programmed proteolysis.
