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Biochem/physiol Actions

Epidermal growth factor receptor (EGFR) has an essential role in normal developmental processes, and is mutated in multiple cancers. It is involved in the pathogenesis of epidermoid tumors, and thus, has extreme importance as a cancer therapeutic target. Gefitinib (GEF) and erlotinib act as EGFR inhibitors, and induce apoptosis in non-small cell lung cancer (NSCLC) cells. A truncated isoform, called EGFRvIII is linked to multiple cases of head and neck squamous cell carcinoma (HNSCC). In ∼40% of glioblastoma multiforme (GBM), this gene is amplified.

EGF exerts its actions by binding to the EGF receptor (EGFR), a 170 kDa glycoprotein having EGF-activated protein tyrosine kinase activity. Even in the absence of EGF-like ligands, EGFR can participate in cellular responses elicited by several other stimuli. High levels of EGFR are expressed in approximately one third of human epithelial tumors, and in the cancers of the bladder, breast or lung that have poor clinical prognosis, hence the interest in targeting EGFR.

General description

Epidermal growth factor receptor (EGFR) belongs to a family of cell surface receptors called receptor tyrosine kinases (RTKs), and is also the most studied member of this family. It is made up of an ectodomain (ECD), which contains four subdomains called DI-DIV, a transmembrane region, and a cytoplasmic tyrosine kinase domain (TKD). Binding of the ligand induces conformational changes in the ECD, which leads to the dimerization of EGFR. This results in the activation of the TKD, and the subsequent signal transduction. This receptor has a molecular weight of ∼178kDa.

Physical form

Lyophilized from a solution in 50 mM HEPES, pH 7.6, 150 mM NaCl, 0.05% Triton X-100, 1 mM dithiothreitol, and 10% trehalose.

Preparation Note

Affinity purified from human carcinoma A431 cells.

Unit Definition

One unit (U) of the enzyme is defined as the amount needed to incorporate 1 pmol of phosphate into the substrate (KVEKIGEGTYGVVYK: 6 - 20 residue of p34cdc2) in 1 minute.