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http://hdl.handle.net/2445/177648
Title: | Tyrosine phosphorylation of ras GTPase activating protein does not require association with the epidermal growth factor receptor |
Author: | Soler Prat, Concepció Beguinot, Laura Sorkin, Alexander Carpenter, Graham |
Keywords: | Proteïnes Proteïna-tirosina-fosfatasa Metabolisme Proteins Protein-tyrosine phosphatase Metabolism |
Issue Date: | 15-Oct-1993 |
Publisher: | American Society for Biochemistry and Molecular Biology |
Abstract: | 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. |
Note: | Reproducció del document publicat a: https://www.jbc.org/issue/S0021-9258(20)X6719-6 |
It is part of: | Journal of Biological Chemistry, 1993, vol. 268, num. 29, p. 22010-22019 |
URI: | http://hdl.handle.net/2445/177648 |
ISSN: | 0021-9258 |
Appears in Collections: | Articles publicats en revistes (Patologia i Terapèutica Experimental) |
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