This gene encodes a member of the epidermal growth factor
(EGF) receptor family of receptor tyrosine kinases. This protein
has no ligand binding domain of its own and therefore cannot bind
growth factors. However, it does bind tightly to other ligand-bound
EGF receptor family members to form a heterodimer, stabilizing
ligand binding and enhancing kinase-mediated activation of
downstream signalling pathways, such as those involving
mitogen-activated protein kinase and phosphatidylinositol-3 kinase.
Allelic variations at amino acid positions 654 and 655 of isoform a
(positions 624 and 625 of isoform b) have been reported, with the
most common allele, Ile654/Ile655, shown here. Amplification and/or
overexpression of this gene has been reported in numerous cancers,
including breast and ovarian tumors. Alternative splicing results
in several additional transcript variants, some encoding different
isoforms and others that have not been fully characterized.
