title: Dynamic glycosylation of nuclear and cytosolic proteins. Cloning and characterization of a unique O-GlcNAc transferase with multiple tetratricopeptide repeats.
abstract: O-Linked N-acetylglucosamine (O-GlcNAc) glycosylation is a dynamic modification of eukaryotic nuclear and cytosolic proteins analogous to protein phosphorylation. We have cloned and characterized a novel gene for an O-GlcNAc transferase (OGT) that shares no sequence homology or structural similarities with other glycosyltransferases. The OGT gene is highly conserved (up to 80% identity) in all eukaryotes examined. Unlike previously described glycosyltransferases, OGT is localized to the cytosol and nucleus. The OGT protein contains multiple tandem repeats of the tetratricopeptide repeat motif. The presence of tetratricopeptide repeats, which can mediate protein-protein interactions, suggests that OGT may be regulated by protein interactions that are independent of the enzyme's catalytic site. The OGT is also modified by tyrosine phosphorylation, indicating that tyrosine kinase signal transduction cascades may play a role in modulating OGT activity.
authors.affiliation: Department of Biochemistry and Molecular Genetics Schools of Medicine/Dentistry, University of Alabama at Birmingham Station, Birmingham, Alabama 35294, USA.
authors.forename: L K
authors.initials: LK
authors.lastname: Kreppel
authors.forename: M A
authors.initials: MA
authors.lastname: Blomberg
authors.forename: G W
authors.initials: GW
authors.lastname: Hart
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000201:enzymology; D017124:Conserved Sequence; D003600:Cytosol / Q000201:enzymology; D019143:Evolution, Molecular; D006031:Glycosylation; D006801:Humans; D008099:Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017351:N-Acetylglucosaminyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D011487:Protein Conformation; D051381:Rats; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping
chemical_list: D009687:Nuclear Proteins; D017351:N-Acetylglucosaminyltransferases; C063057:UDP-N-acetylglucosamine-peptide beta-N-acetylglucosaminyltransferase