Tyrosine phosphorylation of ras GTPase activating protein does not require association with the epidermal growth factor receptor
The importance of the carboxyl-terminal domain of the epidermal growth factor (EGF) receptor and its five autophosphorylation sites in the in vivo interaction and tyrosine phosphorylation of the ras GTPase-activating protein (rasGAP) has been investigated, using NIH 3T3 cells transfected with mutant...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 1993 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/177648 |
| Acceso en línea: | https://hdl.handle.net/2445/177648 |
| Access Level: | acceso abierto |
| Palabra clave: | Proteïnes Proteïna-tirosina-fosfatasa Metabolisme Proteins Protein-tyrosine phosphatase Metabolism |
| Sumario: | The importance of the carboxyl-terminal domain of the epidermal growth factor (EGF) receptor and its five autophosphorylation sites in the in vivo interaction and tyrosine phosphorylation of the ras GTPase-activating protein (rasGAP) has been investigated, using NIH 3T3 cells transfected with mutant EGF receptors. Phosphorylation of rasGAP by EGF receptor mutants, in which one to four autophosphorylation sites (Tyr-1173, -1148, -1086, and -1068) were mutated to phenylalanine, was reduced by 50-60% compared to the wild-type receptor. Elimination of these four autophosphorylation sites by truncation of 123 carboxyl-terminal residues of the EGF receptor paralleled results obtained with point mutants. Substantial inhibition (about 90%) of rasGAP tyrosine phosphorylation by the EGF receptor occurred only when the remaining autophosphorylation site (Tyr-992) was mutated, in the context of this truncated receptor or in the full-length receptor mutated at all four other autophosphorylation sites. However, a point mutation of only Tyr-992 in the full-length receptor suppressed tyrosine phosphorylation of rasGAP only by 50%. In contrast, an EGF receptor lacking the last 214 amino acid residues (Dc214), which encompasses all five autophosphorylation sites, phosphorylated rasGAP to the same extent as the wild-type receptor. However, this truncated receptor was significantly impaired in its capacity to phosphorylate phospholipase C-gamma 1. Interestingly, while EGF receptor autophosphorylation sites are required for EGF-induced rasGAP association with the receptor, maximal phosphorylation of rasGAP by the truncated receptor Dc214 occurred without detectable formation of receptor-rasGAP complexes. Furthermore, the capacity of mutated EGF receptors to bring about focal transformation was correlated with their capacity to phosphorylate rasGAP. |
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