Growth Arrest Specific Protein 6 (GAS6)

Growth arrest-specific 6 is similar to the Protein S with the same domain organization and 43% amino acid identity. GAS6 is a gamma-carboxyglutamic acid (Gla) domain-containing protein thought to be involved in the stimulation of cell proliferation. The gene is expressed as an abundant 2.6-kb mRNA in starved cells but decreases significantly upon stimulation of cells with serum or fibroblast growth factor. A human homolog was isolated from HeLa cells and was predicted to encode a 678-amino acid protein with 81% identity to the mouse protein and 44% identity to human protein S, a vitamin K-dependent negative coregulator in the blood coagulation pathway. Regions of greatest similarity between Gas6 and protein S occur in a gamma carboxylated glutamic acid-rich domain and in 4 EGF-like domains.