Abstract
Small ubiquitin-related modifier (SUMO) is covalently attached to many cellular targets via a three-step enzyme pathway. While the ubiquitination leads to protein degradation, the SUMO modification regulates protein-protein interactions, as well as localization and stability of target proteins. In Arabidopsis, eight SUMO genes are encoded and four of them (AtSUMO1, 2, 3, and 5) are found in the EST database. In order to reveal the functional specificity of each SUMO gene, we analyzed their expression patterns. By the RT-PCR analysis, constitutive expression of AtSUMO1 and 2 was observed, while AtSUMO3 and 5 showed tissue-specific expression. We confirmed the expression of AtSUMO4 in root tissue. Further analysis using the promoter-GUS genes is currently in progress. Furthermore, Arabidopsis has two isoforms, AtSAE1a and b, for the E1 enzyme. We are also analyzing the expression patterns of these genes, respectively.
