Characterization of a high-molecular-weight protein immunoprecipitated by platelet-derived growth factor antisera.
We previously demonstrated that a high-molecular-weight glycoprotein could be immunoprecipitated from metabolically labeled U-2 OS cells with platelet-derived growth factor (PDGF) antiserum and that it appears to be derived from a different precursor than is the 30 kD PDGF-like mitogen produced by these cells. These findings were unexpected, since the molecular weight of this glycoprotein is too large to be encoded by the PDGF structural genes. From experiments with metabolically labeled U-2 OS human osteosarcoma, fibroblasts, and NRK cells, we report here that a 185 kD protein immunoprecipitated with PDGF antiserum has the following characteristics. 1) It is a PDGF binding protein that is unrelated to alpha 2-macroglobulin. 2) It is phosphorylated in response to PDGF stimulation. 3) It is immunoprecipitated by phosphotyrosine antibodies. 4) It is not a substrate of epidermal growth factor-induced tyrosine kinase activity. These studies indicate that high-molecular-weight proteins immunoprecipitated by antiserum to PDGF represent a complex between PDGF and a binding protein capable of being phosphorylated by a PDGF-induced tyrosine kinase. These characteristics are identical to those of the PDGF receptor.
Graves
D T
DT
Department of Periodontics, University of Texas Health Science Center, San Antonio 78284.
Antoniades
H N
HN
D002460:Cell Line; D003429:Cross Reactions; D004815:Epidermal Growth Factor / Q000494:pharmacology; D006801:Humans; D007106:Immune Sera; D008970:Molecular Weight; D010766:Phosphorylation; D019000:Phosphotyrosine; D010982:Platelet-Derived Growth Factor / Q000276:immunology*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000032:analysis* / Q000276:immunology; D017479:Receptors, Platelet-Derived Growth Factor; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
D007106:Immune Sera; D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D019000:Phosphotyrosine; D014443:Tyrosine; D004815:Epidermal Growth Factor; D011505:Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor