Phosphorylation sites in the PDGF receptor with different specificities for binding GAP and PI3 kinase in vivo.

Abstract

Tyrosine residues have been identified in the human platelet‐derived growth factor (PDGF) receptor beta‐subunit whose phosphorylation is stimulated by PDGF. These sites are also in vitro autophosphorylation sites. There are a total of three phosphorylation sites in the kinase insert region, tyrosines 740, 751 and 771. Mutagenesis studies show that Tyr740 and 751 are involved in the PDGF‐stimulated binding of phosphatidylinositol (PI) 3 kinase, and Tyr771 is required for efficient binding of GAP, the GTPase activator of Ras. The requirement for Tyr751 is only detected at low PDGF receptor levels, suggesting that it increases the affinity of binding of PI3 kinase but is not absolutely required. Small deletions in the kinase insert only 10 residues from Tyr740 and Tyr771 do not significantly reduce binding of PI3 kinase or GAP, indicating that distant sequences are probably unimportant for recognition. The data suggest that the receptor signals to different pathways via different phosphorylated tyrosines, and that certain proteins, such as PI3 kinase, can recognize two phosphorylated tyrosines in a single receptor.

Activation of Stat5 by platelet-derived growth factor (PDGF) is dependent on phosphorylation sites in PDGF β-receptor juxtamembrane and kinase insert domains

“…Two autophosphorylation sites in the juxtamembrane domain (Tyr579 and Tyr581) mediate binding of Src family kinases (Mori et al, 1993). Autophosphorylation sites in the kinase insert bind Grb2 (Tyr716; Arvidsson et al, 1994), the regulatory subunit (p85) of phosphatidylinositol 3-kinase (Tyr740 and Tyr751; Fantl et al, 1992;Kashishian et al, 1992), Nck (Tyr751; Nishimura et al, 1993), and the GTPase-activating protein of Ras (Tyr771; Fantl et al, 1992;Kashishian et al, 1992). Two autophosphorylation sites in the C-terminal tail mediate binding of phospholipase C-g (Tyr1009 and Tyr1021; Kashishian and Cooper, 1993;RoÈ nnstrand et al, 1992;Valius et al, 1993), Tyr1009 in addition binds the tyrosine phosphatase SHP2 .…”

Allelic deletion at 11q23.3-q25 is an early event in cervical neoplasia

“…In contrast to insulin, interactions between PDGF receptor and signaling proteins are in many cases direct and do not involve the phosphorylation of a docking protein (such as IRS-1 and IRS-2) with multiple phosphorylation sites serving as targets for SH2 domains. Ligand-induced autophosphorylation of PDGF receptor creates binding sites for a set of signaling proteins, including phospholipase Cg, GTPase activating protein of Ras (GAP), PI 3'-kinase, tyrosine phosphatase Syp, members of the Src family of protein kinases and the adaptor protein Nck (Kazlauskas et al, 1991Kashishian et al, 1992;Ronnstrand et al, 1992;Li et al, 1992;Lechleider et al, 1993). c-Crk is phosphorylated in response to PDGF BB in porcine aortic endothelial cells and is associated in ligand-dependent manner with 72 kDa component related to the adaptor molecule STAM (Hansen et al, 1997).…”

Phosphopeptide binding to the N‐terminal SH2 domain of the p85α subunit of PI 3′‐kinase: A heteronuclear NMR study

“…The p85a protein contains 2 SH2 domains. Two phosphotyrosine sites in the kinase insert of the cytoplasmic domain of the activated human DPDGF receptor, Tyr 740 and Tyr 75 1, are known to associate with these SH2 domains, conceivably with each tyrosine site engaging 1 of the 2 domains (Kashishian et al, 1992). Corresponding synthetic phosphotyrosine-containing peptides are able to block specifically the association of PI 3' kinase with the PDGF receptor (Escobedo et al., 1991;Fantl et al, 1992).…”