Modification of fos proteins: phosphorylation of c-fos, but not v-fos, is stimulated by 12-tetradecanoyl-phorbol-13-acetate and serum

摘要: Abstract We have investigated the covalent modification of proteins encoded by murine fos proto-oncogene (c-fos) and that corresponding gene product FBJ osteosarcoma virus (v-fos). Both are posttranslationally processed in cell, resulting forms with lower electrophoretic mobilities than initial translation on sodium dodecyl sulfate-polyacrylamide gels. Treatment alkaline phosphatase indicates most, if not all, this shift is due to phosphoesterification both proteins. These phosphoryl groups stoichiometrically modify v-fos c-fos serine residues turn over rapidly vivo presence protein kinase inhibitors (half-life, less 15 min). Direct quantitative comparison steady-state labeling studies L-[35S]methionine [32P]phosphate reveals four- fivefold more highly phosphorylated is. Comparison tryptic fragments from [32P]phosphate-labeled although two several phosphopeptides common, contains unique major lacks. sites phosphorylation been tentatively localized carboxy-terminal 20 amino acid protein. Phosphorylation protein, but can be stimulated at least addition either 12-tetradecanoyl-phorbol-13-acetate or serum. This increase degree appears independent C since Ca2+ diacylglycerol independent. The possible role these cellular transformation discussed.