Abstract
Ubiquitin(Ub)/26S proteasome pathway plays an essential housekeeping role to eliminate the proteins which are damaged or misfolded. It is also essential for aspects of cellular regulation by removing short-lived regulatory proteins as a way to fine-tune homeostasis, adapt to new environments, and redirect growth and development. The 26S proteasome consists of two multisubunit complexes, 20S core particle (CP) and 19S regulatory particle (RP). The RP contains three non-ATPase subunits (RPN) and a ring of six AAA-ATPase subunits (RPT). We examined the isolation and characterization of the mutants which are defective in RPT subunit in Arabidopsis, and RPT2a and RPT5a deficient mutants resulted in enlarged leaves, which are caused by accelerated endoreduplication. Endoreduplication is a type of cell cycle where nuclear chromosomal DNA replication occurs without cell division. The function of RPTs will be discussed in terms of cell size regulation.
