Distinct phosphotyrosines on a growth factor receptor bind to specific molecules that mediate different signaling pathways.
The receptor for platelet-derived growth factor (PDGF) binds two proteins containing SH2 domains, GTPase activating protein (GAP) and phosphatidylinositol 3-kinase (PI3-kinase). The sites on the receptor that mediate this interaction were identified by using phosphotyrosine-containing peptides representing receptor sequences to block specifically binding of either PI3-kinase or GAP. These results suggested that PI3-kinase binds two phosphotyrosine residues, each located in a 5 aa motif with an essential methionine at the fourth position C-terminal to the tyrosine. Point mutations at these sites caused a selective elimination of PI3-kinase binding and loss of PDGF-stimulated DNA synthesis. Mutation of the binding site for GAP prevented the receptor from associating with or phosphorylating GAP, but had no effect on PI3-kinase binding and little effect on DNA synthesis. Therefore, GAP and PI3-kinase interact with the receptor by binding to different phosphotyrosine-containing sequence motifs.
Fantl
W J
WJ
Howard Hughes Medical Institute, University of California, San Francisco 94143.
Escobedo
J A
JA
Martin
G A
GA
Turck
C W
CW
del Rosario
M
M
McCormick
F
F
Williams
L T
LT
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D002455:Cell Division; D002478:Cells, Cultured; D006224:Cricetinae; D004252:DNA Mutational Analysis; D020558:GTP Phosphohydrolases / Q000378:metabolism; D020690:GTPase-Activating Proteins; D066298:In Vitro Techniques; D051379:Mice; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases; D010770:Phosphotransferases / Q000378:metabolism*; D019000:Phosphotyrosine; D010982:Platelet-Derived Growth Factor / Q000502:physiology*; D011506:Proteins / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000378:metabolism*; D017479:Receptors, Platelet-Derived Growth Factor; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
D020690:GTPase-Activating Proteins; D010455:Peptides; D010982:Platelet-Derived Growth Factor; D011506:Proteins; D011956:Receptors, Cell Surface; D019000:Phosphotyrosine; D014443:Tyrosine; D010770:Phosphotransferases; D019869:Phosphatidylinositol 3-Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D020558:GTP Phosphohydrolases