Polypeptide N-acetylgalactosaminyltransferase 3 (GALNT3)

Polypeptide N-acetylgalactosaminyltransferase 3 (GALNT3) is an enzyme belonging to the glycosyltransferase family and catalyzes the initial step in mucin-type O-glycosylation, transferring N-acetyl-D-galactosamine to the serine or threonine residues of proteins. GALNT3 is especially important for glycosylating fibroblast growth factor 23 (FGF23), which protects FGF23 from proteolytic cleavage and permits its secretion; intact FGF23 is critical for phosphate homeostasis in humans. Mutations in GALNT3 lead to rare inherited disorders such as hyperphosphatemic familial tumoral calcinosis due to defective FGF23 processing, resulting in excess phosphate retention and ectopic calcifications. GALNT3 has substrate specificity that distinguishes it from other GalNAc transferases, with regulatory implications for bone mineralization and systemic phosphate metabolism. No approved drugs directly target GALNT3, but its involvement in these metabolic pathways suggests potential as a therapeutic target in diseases of phosphate dysregulation.

Other names

GalNAc-T3pp-GaNTase 3polypeptide GalNAc transferase 3polypeptide GalNAc-transferase T3protein-UDP acetylgalactosaminyltransferase 3UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase 3UDP-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase 3HHSHFTCHFTC1GALNAC-T3GALT3_HUMAN

No approved drugs are known to directly target GALNT3; mechanism for potential targeting would involve inhibition or modulation of its glycosyltransferase activity, thereby affecting downstream O-glycosylation of target proteins such as FGF23 (inference based on enzyme function and role in glycosylation).