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p185c-neu and epidermal growth factor receptor associate into a structure composed of activated kinases
X L Quian1, S J Decker, M I Greene
1Department of Biology, University of Pennsylvania, School of Medicine, Philadelphia 19104-6082.
Abstract:
The protein product of the neu protooncogene, p185c-neu, is structurally similar to the epidermal growth factor receptor (EGFR). Overexpression of these two receptor tyrosine kinases, but not either separately, leads to transformation and tumorigenicity. Heterodimerization of p185c-neu and EGFR occurs in M1 cells, which express both receptors. We have individually identified the two components of the heterodimer as EGFR and p185c-neu. Analysis of this association with relatively nondenaturing detergents and in the absence of cross-linkers indicates that noncovalent interactions are primarily responsible for heterodimer formation. The rapid reversible heterodimerization was promoted by EGF binding to its receptor. Functionally, the heterodimer is a highly active protein kinase for receptor autophosphorylation and exogenous substrate phosphorylation in vitro. The isolated heterodimer was highly phosphorylated on tyrosine residues in vivo. These results indicate that the physical association between EGFR and p185c-neu is of functional significance and define enzymatic features of complex receptor formation.
Insights
The neu protooncogene protein (p185c-neu) and epidermal growth factor receptor (EGFR) form a heterodimer. This complex formation, driven by noncovalent bonds and EGF binding, enhances protein kinase activity, impacting cell transformation and tumorigenicity.
Area of Science:
- Molecular Biology
- Cell Signaling
- Oncology
Background:
- p185c-neu and EGFR are receptor tyrosine kinases.
- Overexpression of both, not individually, causes transformation and tumorigenicity.
- M1 cells express both p185c-neu and EGFR, enabling heterodimerization.
Purpose of the Study:
- To investigate the heterodimerization of p185c-neu and EGFR.
- To determine the nature of the association between these receptors.
- To elucidate the functional and enzymatic properties of the EGFR-p185c-neu heterodimer.
Main Methods:
- Analysis of receptor association using nondenaturing detergents.
- Investigating the role of epidermal growth factor (EGF) binding.
- Assessing protein kinase activity and phosphorylation status in vitro and in vivo.
Main Results:
- p185c-neu and EGFR form a heterodimer through noncovalent interactions.
- EGF binding promotes rapid, reversible heterodimerization.
- The heterodimer exhibits high protein kinase activity, including autophosphorylation and substrate phosphorylation.
- The heterodimer is highly tyrosine-phosphorylated in vivo.
Conclusions:
- Physical association between EGFR and p185c-neu is functionally significant.
- Heterodimer formation enhances receptor tyrosine kinase activity.
- This complex formation plays a role in cell transformation and tumorigenicity.