Skip to Content

Ubiquitin ligase activity and tyrosine phosphorylation underlie suppression of growth factor signaling by c-Cbl/Sli-1.

TitleUbiquitin ligase activity and tyrosine phosphorylation underlie suppression of growth factor signaling by c-Cbl/Sli-1.
Publication TypeJournal Article
Year of Publication1999
AuthorsLevkowitz G, Waterman H, Ettenberg SA, Katz M, Tsygankov AY, Alroy I, Lavi S, Iwai K, Reiss Y, Ciechanover A, Lipkowitz S, Yarden Y
JournalMolecular cell
Volume4
Issue6
Pagination1029-40
Date Published1999 Dec
ISSN1097-2765
KeywordsCaenorhabditis elegans Proteins, Cell-Free System, Enzyme Activation, Epidermal Growth Factor, Helminth Proteins, Ligases, Phosphorylation, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-cbl, Receptor, Epidermal Growth Factor, Signal Transduction, Tyrosine, Ubiquitin-Activating Enzymes, Ubiquitin-Protein Ligases
Abstract

Receptor desensitization is accomplished by accelerated endocytosis and degradation of ligand-receptor complexes. An in vitro reconstituted system indicates that Cbl adaptor proteins directly control downregulation of the receptor for the epidermal growth factor (EGFR) by recruiting ubiquitin-activating and -conjugating enzymes. We infer a sequential process initiated by autophosphorylation of EGFR at a previously identified lysosome-targeting motif that subsequently recruits Cbl. This is followed by tyrosine phosphorylation of c-Cbl at a site flanking its RING finger, which enables receptor ubiquitination and degradation. Whereas all three members of the Cbl family can enhance ubiquitination, two oncogenic Cbl variants, whose RING fingers are defective and phosphorylation sites are missing, are unable to desensitize EGFR. Our study identifies Cbl proteins as components of the ubiquitin ligation machinery and implies that they similarly suppress many other signaling pathways.

Alternate JournalMol. Cell


biblio | about seo