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Transmembrane domain of Ephrin Receptor A1 Protein Tyrosine Kinase Ephrin receptors (EphRs) comprise the largest subfamily of receptor PTKs, and are classified into two classes (EphA and EphB), corresponding to binding preferences for either GPI-anchored ephrin-A ligands or transmembrane ephrin-B ligands. Vertebrates have ten EphA and six EphB receptors, which display promiscuous ligand interactions within each class. EphA1 has been associated with late-onset Alzheimer's disease and certain cancers such as colorectal and gastric carcinomas. EphRs contain an ephrin binding domain and two fibronectin repeats extracellularly, a single-span transmembrane (TM) domain, 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. This allows ephrin/EphR dimers to form, leading to the activation of the intracellular tyr kinase domain. The resulting downstream signals occur bidirectionally in both EphR-expressing cells (forward signaling) and ephrin-expressing cells (reverse signaling). The main effect of ephrin/EphR interaction is cell-cell repulsion or adhesion. Ephrin/EphR signaling is important in neural development and plasticity, cell morphogenesis and proliferation, cell-fate determination, embryonic development, tissue patterning, and angiogenesis. The TM domain mediates dimerization. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",