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Mol. Cell. Biol., 10 1996, 5276-5287, Vol 16, No. 10
E Tzahar, H Waterman, X Chen, G Levkowitz, D Karunagaran, S Lavi, BJ Ratzkin and Y Yarden
The ErbB family includes four homologous transmembrane tyrosine kinases.
Whereas ErbB-1 binds to the epidermal growth factor (EGF), both ErbB-3 and
ErbB-4 bind to the Neu differentiation factors (NDFs, or neuregulins), and
ErbB-2, the most oncogenic family member, is an orphan receptor whose
function is still unknown. Because previous lines of evidence indicated the
existence of interreceptor interactions, we used ectopic expression of
individual ErbB proteins and their combinations to analyze the details of
receptor cross talks. We show that 8 of 10 possible homo-and heterodimeric
complexes of ErbB proteins can be hierarchically induced by ligand binding.
Although ErbB-2 binds neither ligand, even in a heterodimeric receptor
complex, it is the preferred heterodimer partner of the three other
members, and it favors interaction with ErbB-3. Selective receptor
overexpression in human tumor cells appears to bias the hierarchical
relationships. The ordered network is reflected in receptor
transphosphorylation, ErbB-2-mediated enhancement of ligand affinities, and
remarkable potentiation of mitogenesis by a coexpressed ErbB-2. The
observed superior ability of ErbB-2 to form heterodimers, in conjunction
with its uniquely high basal tyrosine kinase activity, may explain why
ErbB-2 overexpression is associated with poor prognosis.
Copyright © 1996, American Society for Microbiology
A hierarchical network of interreceptor interactions determines signal transduction by Neu differentiation factor/neuregulin and epidermal growth factor
Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel.
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