Tyrosine-protein kinase Mer (Mer (for MERTK); Axl (for AXL))

Tyrosine-protein kinase Mer is a transmembrane receptor tyrosine kinase encoded by the *MERTK* gene. It is part of the TAM family—which includes TYRO3-, AXL-, and MER-TKs—and features two immunoglobulin-like domains plus two fibronectin type III domains extracellularly with an intracellular catalytic domain.[1][2][5] Its primary physiological functions involve mediating efferocytosis—the recognition and engulfment of apoptotic cells—by macrophages through interaction with ligands such as Gas6 and Protein S.[2] It also acts as a negative regulator within immune responses by suppressing Toll-like receptor signaling at resolution phases. AXL, another member of this family encoded by *AXL*, shares similar structure/function relationships but has distinct expression patterns and disease associations. Both receptors play dual roles—as oncogenes promoting tumor growth/metastasis/drug resistance when overexpressed in cancers,[4][6] while simultaneously limiting excessive inflammation via their immunoregulatory functions.[4] Loss-of-function mutations in *MERTK* cause inherited retinal degenerative disorders like retinitis pigmentosa due to defective phagocytic clearance by retinal pigment epithelial cells.[1] Note: The original query conflates "Tyrosine-protein kinase Mer" (*MERTK*) with "AXL," which are closely related but distinct targets within the same molecular family. Each should ideally be described separately for structured data purposes.

Other names

MER proto-oncogene, tyrosine kinasec-mer proto-oncogene tyrosine kinaseRP38Rdyretinal dystrophy proteinEykNykTyro 12AnexelektoArkTyro7

Drugs typically act as small-molecule inhibitors that block the ATP-binding site of the intracellular tyrosine kinase domain, thereby inhibiting downstream signaling pathways involved in cell proliferation, survival, migration, immune evasion, and phagocytosis suppression. Some may also disrupt ligand binding or dimerization.