Recent Advances in Study for Plant U-box Proteins

U-box domain was a high conserved motif existing widely in eukaryotes,especially in plants.The domain of U-box was similar to that of the RING-finger.Both U-box motif and RING-finger could function as ubiquitin-ligase E3 to catalyze the target proteins ubiquitinated degradation.The U-box motif also was the main functional factor of ubiquitin chain assembly enzyme E4.In plant,U-box usually conjugates with ARM repeats to form the U-box/ARM repeats structure which involved in protein-protein interactions and signal transduction cascade reactions.Many plant U-box proteins could efficiently enhance plants defense to abiotic stresses such as drought,high salinity and abnormal temperature.In addition,U-box proteins were required in plants resistance response to pathogens.