This entry represents the ligand-binding domain found in ephrin type-A receptor 1 (EphA1). Alteration in EphA1 expression levels have been reported in colorectal and gastric cancers, as well as melanomas [, , ]. Class EphA receptors bind GPI-anchored ephrin-A ligands. There are ten vertebrate EphA receptors (EphA1-10), which display promiscuous interactions with six ephrin-A ligands [, ]. Ephrin receptors (EphRs) comprise the largest subfamily of receptor tyrosine kinases (RTKs). EphRs contain a ligand binding domain and two fibronectin repeats extracellularly, a transmembrane segment, and a cytoplasmic tyrosine kinase domain. Binding of the ephrin ligand to EphR requires cell-cell contact since both are anchored to the plasma membrane. The resulting downstream signals occur bidirectionally in both EphR-expressing cells (forward signaling) and ephrin-expressing cells (reverse signaling) [].
