AnxA5

Annexin A5, often abbreviated as AnxA5, is a protein encoded by the *ANXA5* gene in humans. It is a member of the annexin family, a group of calcium-dependent phospholipid-binding proteins. AnxA5 is characterized by its conserved N-terminal domain and a C-terminal domain composed of four homologous repeat units, each containing a conserved aspartic acid residue crucial for calcium binding.

AnxA5 plays a significant role in various cellular processes, including membrane trafficking, apoptosis, and anti-coagulation. Its primary function is to bind to negatively charged phospholipids, particularly phosphatidylserine (PS), on cell membranes. Under normal physiological conditions, PS is sequestered on the inner leaflet of the plasma membrane. However, during apoptosis, PS is translocated to the outer leaflet, making it accessible to AnxA5. This exposure of PS acts as an "eat me" signal, facilitating the recognition and clearance of apoptotic cells by phagocytes.

Beyond its role in apoptosis, AnxA5 is also involved in regulating blood coagulation. It can bind to activated platelets and inhibit the formation of thrombin, thereby exerting an anticoagulant effect. Research has explored the therapeutic potential of AnxA5 in conditions associated with thrombosis and inflammation. Its ability to bind to PS also makes it a useful tool in diagnostic assays for detecting apoptotic cells. The *ANXA5* gene is located on chromosome 4q21.