Function: Ligand for tyrosine-protein kinase receptors AXL, TYRO3 and MER whose signaling is implicated in cell growth and survival, cell adhesion and cell migration. GAS6/AXL signaling plays a role in various processes such as endothelial cell survival during acidification by preventing apoptosis, optimal cytokine signaling during human natural killer cell development, hepatic regeneration, gonadotropin-releasing hormone neuron survival and migration, platelet activation, or regulation of thrombotic responses. Tissue specificity: Plasma. Isoform 1 and isoform 2 are widely expressed. Isoform 1 is the predominant form in spleen. Similarity: Contains 4 EGF-like domains. Contains 1 Gla (gamma-carboxy-glutamate) domain. Contains 2 laminin G-like domains. PTM: Isoform 1 is proteolytically processed after secretion to yield a N-terminal 36 kDa protein and a C-terminal 50 kDa protein including the laminin G-like domains which activates AXL. Gamma-carboxyglutamate residues are formed by vitamin K dependent carboxylation. These residues are essential for the binding of calcium.