title: The heparin-binding site in tetranectin is located in the N-terminal region and binding does not involve the carbohydrate recognition domain.
abstract: Tetranectin is a homotrimeric plasma and extracellular-matrix protein that binds plasminogen and complex sulphated polysaccharides including heparin. In terms of primary and tertiary structure, tetranectin is related to the collectin family of Ca(2+)-binding C-type lectins. Tetranectin is encoded in three exons. Exon 3 encodes the carbohydrate recognition domain, which binds to kringle 4 in plasminogen at low levels of Ca(2+). Exon 2 encodes an alpha-helix, which is necessary and sufficient to govern the trimerization of tetranectin by assembling into a triple-helical coiled-coil structural element. Here we show that the heparin-binding site in tetranectin resides not in the carbohydrate recognition domain but within the N-terminal region, comprising the 16 amino acid residues encoded by exon 1. In particular, the lysine residues in the decapeptide segment KPKKIVNAKK (tetranectin residues 6-15) are shown to be of primary importance in heparin binding.
authors.affiliation: Laboratory of Gene Expression, Department of Molecular and Structural Biology, University of Aarhus, Gustav Wieds Vej 10, DK-8000 Aarhus C, Denmark.
authors.forename: R H
authors.initials: RH
authors.lastname: Lorentsen
authors.forename: J H
authors.initials: JH
authors.lastname: Graversen
authors.forename: N R
authors.initials: NR
authors.lastname: Caterer
authors.forename: H C
authors.initials: HC
authors.lastname: Thogersen
authors.forename: M
authors.initials: M
authors.lastname: Etzerodt
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D001798:Blood Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002846:Chromatography, Affinity; D005091:Exons; D006493:Heparin / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D037102:Lectins / Q000737:chemistry / Q000378:metabolism; D037181:Lectins, C-Type; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010958:Plasminogen / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D001798:Blood Proteins; D037102:Lectins; D037181:Lectins, C-Type; D011994:Recombinant Proteins; C048648:tetranectin; D010958:Plasminogen; D006493:Heparin; D002118:Calcium