earticle

영어

O-GlcNAc is a carbohydrate post-translational modification occurs on hydroxyl groups of serine and/or threonine residues of cytosolic and nuclear proteins. O-GlcNAcase (OGA) is the enzyme that catalyzes the removal of O-GlcNAc moiety on its substrates. It has two isoforms, full OGA and variant OGA, and in early reports it is known that full OGA exists both in cytosol and nucleus, primarily to the cytoplasm. However, there are two opposite reports about the subcellular localization of two OGA isoforms by different research groups. The first group figured out that full OGA localizes in cytoplasm, whereas variant OGA exists within nucleus in 2001. However, recently the other group reported that full OGA localized diffusely throughout the nucleus and cytoplasm, whereas variant OGA resides with lipid droplets in cytosol. So these two finding motivates our laboratory to commence this work as to nucleocytoplasmic shuttling mechanism of two OGA isoforms. We also focus on the various post-translational modifications on OGAs. Full OGA should weigh 103 kDa, but it weighs approximately 130kDa in reality. So we speculate that various modifications might be related to OGA’s subcellular distribution. To verify and get the answers to several issues about OGAs, we first overexpressed two FLAG tagged-OGA isoforms in HeLa cells to trace the subcellular localization of them. Then we made three C-terminal domain deletion mutants to know the critical domain for its localization. And we also check modification occurred on OGAs by using immune-precipitation. Consequentially we can get schematic drawing as to OGA’s nucleocytoplasmic shuttling, and we expect that this research makes it easy to understand and approach O-GlcNAc modification.