GALNT3

The protein encoded by GALNT3 is UDP-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase 3 (GalNAc-T3), commonly known as GalNAc-T3. It initiates mucin-type O-glycosylation by transferring N-acetylgalactosamine from UDP-GalNAc to serine or threonine residues of target proteins, regulating their stability and functional properties.
GalNAc-T3 plays a critical role in glycosylating fibroblast growth factor 23 (FGF23), a key mediator of phosphate homeostasis. Mutations in GALNT3 cause autosomal recessive familial tumoral calcinosis, leading to excessive phosphate retention and soft tissue calcification. Current drug research focuses on correcting FGF23 signaling, though targeted therapies for GALNT3 deficiency remain in preclinical stages.