Cloning and characterization of the murine glucosamine-6-phosphate acetyltransferase EMeg32 - Differential expression and intracellular membrane association

N-Linked glycosylation is a post-translational modification occurring in ma ny eukaryotic secreted and surface-bound proteins and has impact on diverse physiological and pathological processes. Similarly important is the gener ation of glycosylphosphatidylinositol linkers, which anchor membrane protei ns to the cell. Both protein modifications depend on the central nucleotide sugar UDP-N-acetylglucosamine (UDP-GlcNAc). The enzymatic reactions leadin g to generation of nucleotide sugars are established, yet most of the respe ctive genes still await cloning. We describe the characterization of such a gene, EMeg32, which we identified based on its differential expression in murine hematopoietic precursor cells. We further demonstrate regulated expr ession during embryogenesis. EMeg32 codes for a 184-amino acid protein exhi biting glucosamine-6-phosphate acetyltransferase activity. It thereby holds a key position in the pathway toward de novo UDP-GlcNAc synthesis. Surpris ingly, the protein associates with the cytoplasmic side of various intracel lular membranes, accumulates prior to mitosis, and copurifies with the cdc4 8 homolog p97/valosin-containing protein.