Stimulation of the phosphorylation of cytoskeletal 350-kDa and 300-kDa proteins by insulin-like growth factor-I, platelet-derived growth factor and phorbol ester in rat 3Y1 cells.
Insulin-like growth factor-I (IGF-I) stimulated the phosphorylation of cytoskeletal 350-kDa and 300-kDa proteins which were immunoprecipitated with antibodies against brain high molecular weight microtubule-associated proteins in quiescent rat 3Y1 cells. The data on the effective concentrations of IGF-I and 125I-labeled IGF-I binding indicated that type I IGF receptors mediate this IGF-I effect. Platelet-derived growth factor (PDGF) as well as phorbol ester (TPA) also stimulated the phosphorylation of these proteins. These proteins, whether immunoprecipitated from cells stimulated by insulin, IGF-I, TPA, PDGF, or epidermal growth factor, produced very similar phosphopeptide mapping patterns irrespective of the stimulant. The results suggest the possibility that these growth factors and phorbol esters may activate a common protein kinase which is responsible for the phosphorylation of the 350-kDa and 300-kDa proteins in cells.
Nishida
E
E
Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan.
Tobe
K
K
Kadowaki
T
T
Kasuga
M
M
Sato
C
C
Sakai
H
H
D000818:Animals; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008934:Mitogens / Q000494:pharmacology; D010449:Peptide Mapping; D010703:Phorbol Esters / Q000494:pharmacology*; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011494:Protein Kinases / Q000502:physiology; D051381:Rats; D013002:Somatomedins / Q000494:pharmacology*
D003598:Cytoskeletal Proteins; D008934:Mitogens; D010703:Phorbol Esters; D010982:Platelet-Derived Growth Factor; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D011494:Protein Kinases