The hexosamine biosynthetic pathway provides the donor substrate for O-GlcNAcylation and other types of protein glycosylation

The hexosamine biosynthetic pathway provides the donor substrate for O-GlcNAcylation and other types of protein glycosylation. Upon entry into the cell, a small percentage of Glucose (2–5 % in adipocytes) is directed into the hexosamine biosynthetic pathway and converted into UDP-GlcNAc via glutamine:fructose-6-phosphate amidotransferase (GFAT), glucosamine-6-phosphate acetyltransferase (EMeg32), N-acetylglucosamine-phosphate mutase (pgm3), and UDP-GlcNAc pyrophosphorylase (uap1). OGT catalyzes the addition of the glycoside to yield O-GlcNAcylated nuclear, cytoplasmic, and mitochondrial proteins, whereas the enzyme O-GlcNAcase catalyzes the removal O-GlcNAc from proteins. O-GlcNAc-modified proteins are involved in many cellular processes including the cellular stress response. HK hexokinase, G6P-I glucose 6-phosphate isomerase, Glc glucose, NAc N-acetyl

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Dynamic O-GlcNAcylation and its roles in the cellular stress response and homeostasis. (2013) Jennifer A. Groves, et al. Cell Stress Chaperones. 2013 Sep;18(5):535-558. Figure: F1. Homo sapiens

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