?
 
Catalytic domain of the Protein Tyrosine Kinases, Class EphA Ephrin Receptors PTKs catalyze the transfer of the gamma-phosphoryl group from ATP to tyrosine (tyr) residues in protein substrates. This subfamily is composed of most class EphA receptors including EphA3, EphA4, EphA5, and EphA7, but excluding EphA1, EphA2 and EphA10. 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. One exception is EphA4, which also binds ephrins-B2/B3. EphA receptors and ephrin-A ligands are expressed in multiple areas of the developing brain, especially in the retina and tectum. They are part of a system controlling retinotectal mapping. EphRs comprise the largest subfamily of receptor PTKs (RTKs). EphRs contain an ephrin-binding domain and two fibronectin repeats extracellularly, a transmembrane segment, and a cytoplasmic tyr 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). Ephrin/EphR interaction mainly results in cell-cell repulsion or adhesion, making it important in neural development and plasticity, cell morphogenesis, cell-fate determination, embryonic development, tissue patterning, and angiogenesis. The EphA subfamily is part of a larger superfamily that includes the catalytic domains of other kinases such as serine/threonine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",