title: All three potential N-glycosylation sites of the dog kidney (Na+ + K+)-ATPase beta-subunit contain oligosaccharide.
abstract: The beta-subunit of dog kidney (Na+ + K+)-ATPase is a sialoglycoprotein and contains three potential N-glycosylation sites. In this study, the oligosaccharide chains of purified dog kidney beta-subunit were labeled with tritium by oxidation with sodium periodate or galactose oxidase followed by NaB3H4 reduction. The beta-subunit was extensively digested by trypsin and the radioactive peptides were purified by HPLC. The enzyme, glycopeptidase A, which catalyzes the removal of N-linked oligosaccharide chains and the conversion of the glycosylated Asn residue to Asp, was used to demonstrate that a number of purified beta-subunit tryptic peptides were glycosylated. Amino-acid analysis of these beta-subunit peptides following glycopeptidase-A treatment revealed the expected Asn to Asp conversion for Asn-157, Asn-192 and Asn-264, demonstrating that all three potential N-glycosylation sites of the dog kidney beta-subunit are glycosylated. In addition, amino-acid sequence data suggest that a disulfide bond exists between Cys-158 and Cys-174.
authors.affiliation: Department of Physiology and Biophysics, USC School of Medicine, Los Angeles 90033.
authors.forename: R P
authors.initials: RP
authors.lastname: Miller
authors.forename: R A
authors.initials: RA
authors.lastname: Farley
mesh_terms: D000581:Amidohydrolases; D000595:Amino Acid Sequence; D000818:Animals; D004285:Dogs; D006031:Glycosylation; D007679:Kidney Medulla / Q000201:enzymology*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000032:analysis; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D012795:Sialoglycoproteins / Q000032:analysis; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis*
chemical_list: D009844:Oligosaccharides; D012795:Sialoglycoproteins; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D000254:Sodium-Potassium-Exchanging ATPase