Nucleocytoplasmic O-GlcNAc transferase (OGT) attaches a single GlcNAc to hydroxyl groups of serine and threonine residues. Although the cellular localisation of OGT is important to regulate a variety of cellular processes, the molecular mechanisms regulating the nuclear localisation of OGT is unclear. Here, we characterised three amino acids (DFP; residues 451-453) as the nuclear localisation signal of OGT and demonstrated that this motif mediated the nuclear import of non-diffusible β-galactosidase. OGT bound the importin α5 protein, and this association was abolished when the DFP motif of OGT was mutated or deleted. We also revealed that O-GlcNAcylation of Ser389, which resides in the tetratricopeptide repeats, plays an important role in the nuclear localisation of OGT. Our findings may explain how OGT, which possesses a NLS, exists in the nucleus and cytosol simultaneously.
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We are grateful to David Vocadlo at Simon Fraser University (Canada) for providing 5-thio-GlcNAc (OGT inhibitor), Priska von Haller and Jimmy K. Eng at the University of Washington's Proteomics Resource (USA) for Orbitrap Fusion MS data acquisition and database searching. This research was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (NRF-2013R1A2A1A01008067) to J.W.C., (NRF-2015M3A9B6073840 and NRF-2016R1A5A1010764) to J.W.C. and E.C.Y. This research was also supported by the Ministry of Science, ICT and Future Planning (NRF-2012M3A9B9036669 to E.C.Y., 2015R1C1A1A02037274 to M.J.K.), and the Korea Health Technology R and D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health and Welfare, Republic of Korea (HI14C1277) to E.C.Y.
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