title: Glycosylation sites identified by detection of glycosylated amino acids released from Edman degradation: the identification of Xaa-Pro-Xaa-Xaa as a motif for Thr-O-glycosylation.
abstract: Here we report the use of automated Edman degradation of covalently linked glycopeptides to identify positively the sites of O- and N-glycosylation. The O-glycosidic linkage of carbohydrate to the hydroxy amino acids Ser and Thr is a major form of post-translational modification. However, unlike Asn-linked glycosylation, which is identified by the consensus sequence Asn-Xaa-Thr/Ser, no simple motif conferring O-linkage to Thr and Ser has been described. After sequencing glycopeptides derived from two cell surface glycoproteins, a Thr-O-glycosylation motif of Xaa-Pro-Xaa-Xaa, where at least one Xaa = Thr(Sac), has been defined. This motif predicts the site(s) of Pro- associated Thr-O-glycosylation in O-glycosylated proteins, although it is clear that there are also other forms of Thr-O-glycosylation not associated with Pro.
authors.affiliation: School of Biological Sciences, Macquarie University, Sydney, N.S.W. Australia.
authors.forename: A A
authors.initials: AA
authors.lastname: Gooley
authors.forename: B J
authors.initials: BJ
authors.lastname: Classon
authors.forename: R
authors.initials: R
authors.lastname: Marschalek
authors.forename: K L
authors.initials: KL
authors.lastname: Williams
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D006020:Glycopeptides / Q000302:isolation & purification*; D006031:Glycosylation; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification; D011392:Proline; D011506:Proteins / Q000235:genetics*; D051381:Rats; D012694:Serine; D013912:Threonine; D014162:Transfection
chemical_list: D006020:Glycopeptides; D010446:Peptide Fragments; D011506:Proteins; D013912:Threonine; D012694:Serine; D011392:Proline