O-GlcNAc, an essential regulator of numerous cellular pathways

Published on March 13, 2014   49 min

Other Talks in the Series: Glycobiology

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Welcome to this lecture for Henry Stewart Talks in which we will discuss the O-GIcNAc modification and its essential regulatory role in numerous cellular pathways. My name is Natasha Zachara and I'm a member of the Department of Biological Chemistry at the Johns Hopkins University School of Medicine.
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We will start by defining, what is O-GIcNAc or O-GIcNAcylation? The O-GIcNAc modification or O-GIcNAcylation is the modification of nuclear, cytoplasmic, and mitochondrial protein by monosaccharides of O-linked beta-N-acetyl-D-glucosamine. O-GIcNAc is added and removed dynamically by just two enzymes, the O-GIcNAc transferase, shortened to OGT, catalyzes the addition of O-GIcNAc. And O-GIcNAc is removed by neutral N-acetylglucasaminidase, known as O-GIcNAcase. O-GIcNAc is common in metazoans, but there is also evidence for this modification in Aspergilus, protozoa, and Listeria. O-GIcNAc has long been considered a novel form a protein glycosylation for three reasons. Firstly, its localization. Unlike prototypical glycosylation, which is added in the ER and Golgi, the addition and removal of O-GIcNAc is catalyzed in the nucleus, the cytoplasm, and the mitochondria. And, in fact, the protein modified by O-GIcNAc exist in the same loci rather than in the endomembrane system. The addition and removal of O-GIcNAc is very dynamic. Thus, the sugar is added and removed to proteins many times during their lifetime. And, finally, with the exception of nuclear pore proteins, O-GIcNAc is not further modified into more complex glycan structures.
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O-GlcNAc, an essential regulator of numerous cellular pathways

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