title: Identification of three amino acids in the platelet-derived growth factor (PDGF) B-chain that are important for binding to the PDGF beta-receptor.
abstract: Platelet-derived growth factor (PDGF) is a disulfide-linked dimeric protein composed of two homologous polypeptide chains denoted A and B. Two types of PDGF receptors, alpha and beta, have been characterized. Whereas PDGF-AA binds only to PDGF alpha-receptors, PDGF-BB binds to both receptor types with high affinity. To map the regions of the PDGF B-chain that confer its ability to bind with high affinity to the PDGF beta-receptor, we expressed PDGF A/B-chain chimeras in COS cells and analyzed them with regard to PDGF alpha- and beta-receptor binding. A systematic analysis revealed that replacement of Asn-115, Arg-154, and Ile-158 of the PDGF B-chain with the corresponding A-chain amino acids led to a dramatic decrease in the affinity for the beta-receptor. Conversely, introduction of B-chain amino acids into the A-chain in the region spanning from Asn-115 to Ile-158 yielded a product with high affinity for the beta-receptor. These data thus indicate that Asn-115, Arg-154, and Ile-158 are likely to be part of the active site of the PDGF B-chain.
authors.affiliation: Ludwig Institute for Cancer Research, Biomedical Center, Uppsala, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Ostman
authors.forename: M
authors.initials: M
authors.lastname: Andersson
authors.forename: U
authors.initials: U
authors.lastname: Hellman
authors.forename: C H
authors.initials: CH
authors.lastname: Heldin
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism*; D002460:Cell Line; D002678:Chimera; D004247:DNA / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D010982:Platelet-Derived Growth Factor / Q000235:genetics / Q000378:metabolism*; D011233:Precipitin Tests; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017479:Receptors, Platelet-Derived Growth Factor; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D000596:Amino Acids; D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D004247:DNA; D017479:Receptors, Platelet-Derived Growth Factor