Open AccessIdentification of an Ubiquitin‐Ligation System for the Epidermal‐Growth‐Factor Receptor
Author(s) -
Mori Seijiro,
Tanaka Keiji,
Kanaki Harumi,
Nakao Mitsuyoshi,
Anan Tadashi,
Yokote Koutaro,
Tamura Ken,
Saito Yasushi
Publication year - 1997
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1997.01190.x
Subject(s) - reticulocyte , ubiquitin , ubiquitin ligase , tyrosine kinase , epidermal growth factor , ubiquitin conjugating enzyme , biochemistry , biology , receptor , epidermal growth factor receptor , receptor tyrosine kinase , microbiology and biotechnology , gene , messenger rna
Some receptor tyrosine kinases such as the receptors for epidermal‐growth factor (EGF) and platelet‐derived growth factor undergo polyubiquitination as a consequence of ligand binding. The EGF receptor is also ubiquitinated by treatment with herbimycin A, an ansamycin antibiotic widely used as a tyrosine kinase inhibitor. To investigate the mechanism of the receptor ubiquitination, we have established an assay system in which herbimycin‐A‐induced ubiquitination processes can be analyzed in vitro. We now show that herbimycin A treatment of the purified EGF receptor induces polyubiquitination of the receptor in rabbit‐reticulocyte lysate. Both DEAE unadsorbed material (fraction I) and high salt eluate (fraction II) of the reticulocyte lysate are involved cooperatively in the ubiquitination process, where the ubiquitin‐conjugating enzyme UBC4 can functionally substitute for fraction I. A ubiquitin‐protein ligase‐like activity, partially purified from fraction II by DEAE anion‐exchange chromatography, also functions in concert with UBC4. The precise mechanism of herbimycin A‐induced ubiquitination of the EGF receptor is not fully understood, however, our present findings suggest that direct interaction with herbimycin A results in some modification of the receptor which is recognized by the ubiquitin‐conjugating system in rabbit‐reticulocyte lysate.