Examination of the role of serine phosphorylation in phospholipase C-gamma and its related P47 in cAMP-mediated depression of epidermal growth factor signal transduction.
Forskolin-pretreatment of A431 cells reduced both intrinsic and epidermal growth factor (EGF)-induced EGF receptor phosphorylation, however, phosphorylation of phospholipase C-gamma (PLC-gamma) was stimulated under the same conditions. No significant difference was detected in the amount of phosphotyrosine of PLC-gamma between two cultures with or without forskolin treatment followed by EGF. On the other hand, phosphorylation of a 47 kDa protein (P47) which cross-reacted with an anti-PLC-gamma monoclonal antibody, was stimulated by both forskolin and EGF. Phosphorylation was exclusively on serine residues in this case. These results indicate that both PLC-gamma and P47 are phosphorylated by a cAMP-dependent protein kinase and the EGF-stimulated serine kinase, and suggest that serine phosphorylation of PLC-gamma has no effect on ligand-dependent coupling with the EGF receptor.
Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan.
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K
Mitsui
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S
Iwashita
D005576:Colforsin / Q000494:pharmacology; D003429:Cross Reactions; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008970:Molecular Weight; D010449:Peptide Mapping; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D019000:Phosphotyrosine; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000276:immunology / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D010768:Phosphoserine; D005576:Colforsin; D019000:Phosphotyrosine; D014443:Tyrosine; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D010738:Type C Phospholipases