This entry represents the SAM (sterile alpha motif) domain of EPH-A6 (Ephrin type-A receptor 6), a receptor tyrosine kinase. It is a C-terminal potential protein-protein interaction domain located in the cytoplasmic region of EPH-A6 receptors and appears to mediate cell-cell initiated signal transduction []. Eph-A6 gene is preferentially expressed in the nervous system. EPH-A6 receptors are involved in primate retina vascular and axon guidance, and in neural circuits responsible for learning and memory []. EphA6 gene was significantly down regulated in colorectal cancer and in malignant melanomas. It is a potential molecular marker for these cancers [, ].
This entry represents the ligand-binding domain found in ephrin type-A receptor 6 (EphA6). EphA6, like other Eph receptors and their ephrin ligands, seems to play a role in neural development, underlying learning and memory []. EphA6 has also been implicated in retinal vascular patterning [].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) [].
