TAM Receptor

TAM receptors, comprising of Tyro3, Axl and Mertk receptors, are receptor tyrosine kinases (RTKs) that are expressed by multiple immune cells including NK cells. The TAM family of receptors and their ligands Gas6 and Protein S (PROS1) are required for the optimal phagocytosis of apoptotic cells in the mature immune, nervous, and reproductive systems.

TAMs are three homologous type I receptor-tyrosine kinases that are activated by endogenous ligands, PROS1 and GAS6. These ligands can either activate TAMs as soluble factors, or, in turn, opsonize phosphatidylserine (PS) on apoptotic cells (ACs) and serve as bridging molecules between ACs and TAMs. Abnormal expression and activation of TAMs have been implicated in promoting proliferation and survival of cancer cells, as well as in suppressing anti-tumor immunity.