Dissociation of the ligand and dephosphorylation of the platelet-derived growth factor receptor.
The ligand-induced phosphorylation of the platelet-derived growth factor (PDGF) receptor was followed at 37 degrees C by a rapid dephosphorylation which was roughly parallel to the down regulation of the 125I-PDGF binding sites. At 4 degrees C, when the ligand-receptor complexes remain associated with the cell surface, the phosphorylated form of the receptor was more stable. However if the ligand was dissociated from the receptor by means of a mild acid wash or a treatment with suramin, the dephosphorylation of the receptor also occurred at a low temperature. These data suggest that, due to the dissociation of the ligand, the kinase activity of the receptor is switched off so that the phosphotyrosine-containing receptors remain exposed to the action of phosphatases that rapidly dephosphorylate them.
Sturani
E
E
Dipartimento di Fisiologia e Biochimica Generali, Università di Milano, Italy.
Zippel
R
R
Morello
L
L
Brambillo
R
R
Alberghina
L
L
D000818:Animals; D002478:Cells, Cultured; D007700:Kinetics; D051379:Mice; D010766:Phosphorylation; D019000:Phosphotyrosine; D010982:Platelet-Derived Growth Factor / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017479:Receptors, Platelet-Derived Growth Factor; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D019000:Phosphotyrosine; D014443:Tyrosine; D017479:Receptors, Platelet-Derived Growth Factor