Distribution of O-GlcNAc transferase in the rat pancreas

O-GlcNAc transferase (OGT) catalyzes the attachment of N-acetylglucosamine monosaccharides to the hydroxyl group of serine or threonine residues of in tracellular proteins and may play an important role in the hexosamine pathw ay. We examined the localization of OGT protein in the rat pancreas. Immuno fluorescence staining with antibody raised against OGT stained both the exo crine acinar cells and endocrine islet cells. The acinar cell nucleus and t he zymogen granule region were intensely stained. In the islets of Langerha ns, especially in the A cells, intense staining with anti-OGT antibody was observed. Immune-electron microscopy showed the OGT to be restricted to the euchromatin of the nucleus and around the secretory granules of exocrine a cinar cells and endocrine islet cells. These results suggest that OGT is in volved in the regulation of transcription and of granular secretion. Thus. O-GlcNAcylated protein(s) may be an important component of the glucose-sens ing mechanism in the pancreas.