Tyro/Axl/Mer激活
Axl, Mer and Tyro3 are three members of the TAM family receptor tyrosine kinase that share a common NCAM (neural adhesion molecule)-related extracellular domain and a conserved intracellular tyrosine kinase domain. These receptors bind common homologous vitamin K dependent protein GAS6 and protein S to activate downstream signaling pathways. TAM family receptors are involved in the development of immune, nervous, vascular and reproductive systems, autoimmune disease, cancer drug resistance and tumor immunity response. Axl (Tyr698), Axl (Tyr702), Mer Tyr(749) and Tyro3 (Tyr681) are conserved autophosphorylation sites located in the activation loop of the respective tyrosine kinase domains. Phosphorylation at these sites is required for full kinase activation of each of the corresponding receptors.