N-acetylglucosamine-1-phosphotransferase subunit gamma (GNPTG)

N-acetylglucosamine-1-phosphotransferase subunit gamma (GNPTG) is a key component of the hexameric enzyme complex (alpha2-beta2-gamma2) that catalyzes the first step in the formation of the mannose 6-phosphate (M6P) recognition marker on lysosomal acid hydrolases (UniProt P59817). This modification is essential for the proper sorting and transport of these enzymes from the Golgi apparatus to the lysosome (PubMed: 12446702). While the alpha and beta subunits contain the catalytic activity, the gamma subunit is thought to play a role in substrate recognition and enhancing the efficiency of the phosphotransferase reaction (PubMed: 15546861). Mutations in the GNPTG gene result in Mucolipidosis type III gamma (ML III gamma), a lysosomal storage disorder characterized by skeletal dysplasia, joint stiffness, and mild developmental delays due to the extracellular secretion of enzymes that should have been targeted to the lysosome (OMIM: 252605). Currently, there are no approved small-molecule drugs that directly target GNPTG; however, it is a significant target for gene therapy and enzyme replacement research aimed at correcting the underlying biochemical defect in ML III gamma patients (PubMed: 30335157).

Other names

GlcNAc-phosphotransferase subunit gammaUDP-N-acetylglucosamine-1-phosphotransferase subunit gammaGNPTAGUDP-N-acetylglucosamine-1-phosphotransferase subunit g

Restoration of mannose 6-phosphate (M6P) recognition marker synthesis through gene replacement or enzyme enhancement (investigational).