Galnac-T3 (GALNT3) Active Protein

This gene encodes UDP-GalNAc transferase 3, a member of the GalNAc-transferases family. This family transfers an N-acetyl galactosamine to the hydroxyl group of a serine or threonine residue in the first step of O-linked oligosaccharide biosynthesis. Individual GalNAc-transferases have distinct activities and initiation of O-glycosylation is regulated by a repertoire of GalNAc-transferases. The protein encoded by this gene is highly homologous to other family members, however the enzymes have different substrate specificities. [provided by RefSeq, Jul 2008]

GALNT3: an enzyme that catalyzes the initial reaction in O-linked oligosaccharide biosynthesis, the transfer of an N-acetyl-D-galactosamine residue to a serine or threonine residue on the protein receptor. A single-pass type II membrane protein that localizes to the Golgi apparatus membrane. Has activity toward HIV envelope glycoprotein gp120, EA2, Muc2 and Muc5. Probably glycosylates fibronectin in vivo. Plays a central role in phosphate homeostasis. Mutations cause cause familial tumoral calcinosis, a severe autosomal recessive metabolic disorder that manifests with hyperphosphatemia and massive calcium deposits in the skin and subcutaneous tissues. Overexpressed in many differentiated carcinomas, suggesting that it may serve as a marker of tumor differentiation. Two alternatively spliced human isoforms have been described.

Protein type: EC 2.4.1.41; Glycan Metabolism - O-glycan biosynthesis; Membrane protein, integral; Transferase

Chromosomal Location of Human Ortholog: 2q24.3

Cellular Component: extracellular exosome; Golgi apparatus; Golgi membrane; integral component of membrane; membrane; perinuclear region of cytoplasm

Molecular Function: calcium ion binding; carbohydrate binding; manganese ion binding; polypeptide N-acetylgalactosaminyltransferase activity

Biological Process: carbohydrate metabolic process; fibroblast growth factor receptor signaling pathway; O-glycan processing; protein O-linked glycosylation via serine; protein O-linked glycosylation via threonine

Disease: Tumoral Calcinosis, Hyperphosphatemic, Familial