PDGF stimulation of inositol phospholipid hydrolysis requires PLC-gamma 1 phosphorylation on tyrosine residues 783 and 1254.
PDGF binding to its receptor promotes the association with and stimulates the phosphorylation of PLC-gamma 1 at tyrosine and serine residues. Also, PDGF induces an increase in the hydrolysis of inositol phospholipids by PLC. How PDGF activates PLC was investigated by substituting phenylalanine for tyrosine at PLC-gamma 1 phosphorylation sites 771, 783, and 1254 and expressing the mutant enzymes in NIH 3T3 cells. Phenylalanine substitution at Tyr-783 completely blocked the activation of PLC by PDGF, whereas mutation at Try-1254 inhibited and mutation at Tyr-771 enhanced the response. Like the wild type, PLC-gamma 1 substituted with phenylalanine at Tyr-783 became associated with the PDGF receptor and underwent phosphorylation at serine residues in response to PDGF. These results suggest that PLC-gamma 1 is the PLC isozyme that mediates PDGF-induced inositol phospholipid hydrolysis, that phosphorylation on Tyr-783 is essential for PLC-gamma 1 activation. These results provide direct evidence that growth factor receptors activate the function of intracellular protein by tyrosine phosphorylation.
Kim
H K
HK
Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892.
Kim
J W
JW
Zilberstein
A
A
Margolis
B
B
Kim
J G
JG
Schlessinger
J
J
Rhee
S G
SG
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D006868:Hydrolysis; D007527:Isoenzymes / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000032:analysis; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine; D010982:Platelet-Derived Growth Factor / Q000378:metabolism / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000378:metabolism; D017479:Receptors, Platelet-Derived Growth Factor; D012694:Serine / Q000378:metabolism; D014162:Transfection; D010738:Type C Phospholipases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis / Q000378:metabolism*
D007527:Isoenzymes; D010455:Peptides; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D019000:Phosphotyrosine; D014443:Tyrosine; D012694:Serine; D017479:Receptors, Platelet-Derived Growth Factor; D010738:Type C Phospholipases