title: Tissue plasminogen activator has an O-linked fucose attached to threonine-61 in the epidermal growth factor domain.
abstract: An unusual type of glycosylation has been observed for tissue plasminogen activator (t-PA). The monosaccharide fucose is glycosidically linked to threonine-61 in the epidermal growth factor region of t-PA. The presence of O-linked fucose was demonstrated by carbohydrate analysis and mass spectrometry of tryptic and chymotryptic peptides that contain this site. The susceptibility of the fucose residue to alpha-fucosidase indicated that it was in the alpha-anomeric configuration. Fucosylation of threonine-61 was observed in t-PA isolated from the Bowes melanoma cell line and from recombinant expression systems using Chinese hamster ovary or human embryonic kidney cells. Fucosylation of the homologous residue in prourokinase has also been reported recently. Our results indicate that this novel type of glycosylation may be common to the epidermal growth factor domains found in coagulation and fibrinolytic proteins and, therefore, suggest that the modification may have functional significance.
authors.affiliation: Department of Medicinal and Analytical Chemistry, Genentech, Inc., South San Francisco, California 94080.
authors.forename: R J
authors.initials: RJ
authors.lastname: Harris
authors.forename: C K
authors.initials: CK
authors.lastname: Leonard
authors.forename: A W
authors.initials: AW
authors.lastname: Guzzetta
authors.forename: M W
authors.initials: MW
authors.lastname: Spellman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D002918:Chymotrypsin; D004815:Epidermal Growth Factor / Q000235:genetics; D005643:Fucose / Q000032:analysis*; D006031:Glycosylation; D006801:Humans; D008545:Melanoma / Q000201:enzymology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification; D010449:Peptide Mapping; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification; D013912:Threonine; D010959:Tissue Plasminogen Activator / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D014357:Trypsin
chemical_list: D010446:Peptide Fragments; D011994:Recombinant Proteins; D005643:Fucose; D013912:Threonine; D004815:Epidermal Growth Factor; D002918:Chymotrypsin; D014357:Trypsin; D010959:Tissue Plasminogen Activator