title: Role of spacer-1 in the maturation and function of GlcNAc-1-phosphotransferase.
abstract: The UDP-GlcNAc:lysosomal enzyme, N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-PT), is an α2β2γ2hexamer that mediates the initial step in the formation of the mannose 6-phosphate targeting signal on newly synthesized lysosomal acid hydrolases. The GNPTAB gene encodes the 1256 amino acid long α/β precursor which is normally cleaved at K928 in the early Golgi by Site-1 protease (S1P). Here, we show that removal of the so-called 'spacer-1' domain (residues 86-322) results in cleavage almost exclusively at a second S1P consensus sequence located upstream of K928. In addition, GlcNAc-1-PT lacking spacer-1 exhibits enhanced phosphorylation of several non-lysosomal glycoproteins, while the phosphorylation of lysosomal acid hydrolases is not altered. In view of these effects on the maturation and function of GlcNAc-1-PT, we suggest renaming `spacer-1' the `regulatory-1' domain.
authors.affiliation: Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: Wang-Sik
authors.initials: WS
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: Balraj
authors.initials: B
authors.lastname: Doray
authors.affiliation: Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: Stuart
authors.initials: S
authors.lastname: Kornfeld
mesh_terms: D004023:Dictyostelium / Q000201:enzymology; D006023:Glycoproteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008247:Lysosomes / Q000378:metabolism; D050505:Mutant Proteins / Q000378:metabolism; D010766:Phosphorylation; D000072417:Protein Domains; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D017855:Transferases (Other Substituted Phosphate Groups) / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D006023:Glycoproteins; D050505:Mutant Proteins; D017855:Transferases (Other Substituted Phosphate Groups); C030012:UDP-N-acetylglucosamine-lysosomal-enzyme-N-acetylglucosaminephosphotransferase
keywords: GlcNAc-1-phosphotransferase; lysosomal enzyme; mannose 6-phosphate; site-1 protease; spacer domain