Phospholipase C-gamma 1 and phosphatidylinositol 3 kinase are the downstream mediators of the PDGF receptor's mitogenic signal. 1993

M Valius, and A Kazlauskas
National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado 80206.

Upon ligand-induced tyrosine phosphorylation, the platelet-derived growth factor (PDGF) receptor (PDGFR) beta subunit associates with PLC-gamma 1, RasGAP, P13K, and a 64 kd protein. To determine the relative role of each of these associated proteins in PDGFR signaling, we constructed a PDGFR mutant (F5) unable to bind any of them and a panel of "add-back" mutants that could bind only one of the receptor-associated proteins. F5 PDGFR failed to activate PLC-gamma 1, P13K, or Ras and was unable to trigger DNA synthesis. Permitting association of F5 PDGFR with either PLC-gamma 1 or P13K restored Ras activation and a mitogenic response. Surprisingly, even though binding of the 64 kd protein almost fully restored Ras activation, it did not rescue the receptor's ability to trigger DNA synthesis. Thus Ras activation is insufficient to trigger PDGF-dependent DNA synthesis, and PLC-gamma 1 and P13K are independent downstream mediators of PDGF's mitogenic signal.

UI MeSH Term Description Entries
D008938 Mitosis A type of CELL NUCLEUS division by means of which the two daughter nuclei normally receive identical complements of the number of CHROMOSOMES of the somatic cells of the species. M Phase, Mitotic,Mitotic M Phase,M Phases, Mitotic,Mitoses,Mitotic M Phases,Phase, Mitotic M,Phases, Mitotic M
D010738 Type C Phospholipases A subclass of phospholipases that hydrolyze the phosphoester bond found in the third position of GLYCEROPHOSPHOLIPIDS. Although the singular term phospholipase C specifically refers to an enzyme that catalyzes the hydrolysis of PHOSPHATIDYLCHOLINE (EC 3.1.4.3), it is commonly used in the literature to refer to broad variety of enzymes that specifically catalyze the hydrolysis of PHOSPHATIDYLINOSITOLS. Lecithinase C,Phospholipase C,Phospholipases, Type C,Phospholipases C
D010770 Phosphotransferases A rather large group of enzymes comprising not only those transferring phosphate but also diphosphate, nucleotidyl residues, and others. These have also been subdivided according to the acceptor group. (From Enzyme Nomenclature, 1992) EC 2.7. Kinases,Phosphotransferase,Phosphotransferases, ATP,Transphosphorylase,Transphosphorylases,Kinase,ATP Phosphotransferases
D010982 Platelet-Derived Growth Factor Mitogenic peptide growth hormone carried in the alpha-granules of platelets. It is released when platelets adhere to traumatized tissues. Connective tissue cells near the traumatized region respond by initiating the process of replication. Platelet Derived Growth Factor,Factor, Platelet-Derived Growth,Growth Factor, Platelet-Derived
D011505 Protein-Tyrosine Kinases Protein kinases that catalyze the PHOSPHORYLATION of TYROSINE residues in proteins with ATP or other nucleotides as phosphate donors. Tyrosine Protein Kinase,Tyrosine-Specific Protein Kinase,Protein-Tyrosine Kinase,Tyrosine Kinase,Tyrosine Protein Kinases,Tyrosine-Specific Protein Kinases,Tyrosylprotein Kinase,Kinase, Protein-Tyrosine,Kinase, Tyrosine,Kinase, Tyrosine Protein,Kinase, Tyrosine-Specific Protein,Kinase, Tyrosylprotein,Kinases, Protein-Tyrosine,Kinases, Tyrosine Protein,Kinases, Tyrosine-Specific Protein,Protein Kinase, Tyrosine-Specific,Protein Kinases, Tyrosine,Protein Kinases, Tyrosine-Specific,Protein Tyrosine Kinase,Protein Tyrosine Kinases,Tyrosine Specific Protein Kinase,Tyrosine Specific Protein Kinases
D011506 Proteins Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein. Gene Products, Protein,Gene Proteins,Protein,Protein Gene Products,Proteins, Gene
D004247 DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D004252 DNA Mutational Analysis Biochemical identification of mutational changes in a nucleotide sequence. Mutational Analysis, DNA,Analysis, DNA Mutational,Analyses, DNA Mutational,DNA Mutational Analyses,Mutational Analyses, DNA
D004789 Enzyme Activation Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme. Activation, Enzyme,Activations, Enzyme,Enzyme Activations
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man

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