Demonstration of Functionally Different Interactions between Phospholipase C-γ and the Two Types of Platelet-derived Growth Factor Receptors(∗)

• Published in: The Journal of biological chemistry 1995-03, Vol.270 (13), p.7773-7781
• Main Authors: Nånberg, Eewa, Rupp, Eva, Carpenter, Graham, Eriksson, Anders, Rönnstrand, Lars, Engström, Ulla, Hellman, Ulf, Heldin, Carl-Henrik, Claesson-Welsh, Lena
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Aorta; Base Sequence; Becaplermin; Binding, Competitive; Cell Division; Endothelium, Vascular - metabolism; Isoenzymes - metabolism; Kinetics; Molecular Sequence Data; Mutagenesis, Site-Directed; Oligodeoxyribonucleotides; Peptide Fragments - chemistry; Peptide Fragments - isolation & purification; Phospholipases - metabolism; Phosphopeptides - pharmacology; Phosphorylation; Phosphotyrosine; Platelet-Derived Growth Factor - pharmacology; Point Mutation; Proto-Oncogene Proteins c-sis; Receptor Protein-Tyrosine Kinases - metabolism; Receptor, Platelet-Derived Growth Factor alpha; Receptor, Platelet-Derived Growth Factor beta; Receptors, Platelet-Derived Growth Factor - metabolism; Recombinant Proteins - pharmacology; Sequence Homology, Amino Acid; Swine; Thymidine - metabolism; Tyrosine - analogs & derivatives; Tyrosine - metabolism
• ISSN: 0021-9258; 1083-351X; 1083-351X
• DOI: 10.1074/jbc.270.13.7773

Phosphorylated tyrosine residues in receptor tyrosine kinases serve as binding sites for signal transduction molecules. We have identified two autophosphorylation sites, Tyr-988 and Tyr-1018, in the platelet-derived growth factor (PDGF) α-receptor carboxyl-terminal tail, which are involved in binding of phospholipase C-γ (PLC-γ). The capacities of the Y988F and Y1018F mutant PDGF α-receptors, expressed in porcine aortic endothelial cells, to bind PLC-γ are 60 and 5% of that of the wild-type receptor, respectively. Phosphorylated but not unphosphorylated peptides containing Tyr-1018 are able to compete with the intact receptor for binding to immobilized PLC-γ SH2 domains; a phosphorylated Tyr-988 peptide competes 10 times less efficiently. The complex between PLC-γ and the PDGF α-receptor is more stable than that of PLC-γ and the PDGF β-receptor. However, PDGF stimulation results in a smaller fraction of tyrosine-phosphorylated PLC-γ and a smaller accumulation of inositol trisphosphate in cells expressing the α-receptor as compared with cells expressing the β-receptor. We conclude that phosphorylated Tyr-988 and Tyr-1018 in the PDGF α-receptor carboxyl-terminal tail bind PLC-γ, but this association leads to only a relatively low level of tyrosine phosphorylation and activation of PLC-γ.