Annexin A5 (ANXA5) (ANXA5)

Annexin A5, commonly known as Annexin V, is a member of the annexin family of calcium-dependent phospholipid-binding proteins that plays a pivotal role in regulating membrane dynamics and coagulation. It is distinguished by its exceptional affinity for phosphatidylserine (PS), a phospholipid that is typically sequestered in the inner plasma membrane but becomes exposed on the cell surface during apoptosis or platelet activation [Source: UniProt, P08758]. By binding to exposed PS, Annexin A5 acts as a potent anticoagulant, shielding the phospholipid from the assembly of pro-coagulant tenase and prothrombinase complexes [Source: PubMed, 15134468]. Beyond its role in coagulation, Annexin A5 is widely utilized in biotechnology as a diagnostic tool for detecting apoptosis and is being investigated as a therapeutic agent for conditions such as atherosclerosis, myocardial infarction, and ischemia-reperfusion injury [Source: PubMed, 26458231]. Other family members, notably Annexin A1, are essential mediators of the anti-inflammatory effects of glucocorticoids, acting through the Formyl Peptide Receptor 2 (FPR2) to promote the resolution of inflammation [Source: PubMed, 21844396]. Consequently, the annexin family represents a versatile target for both molecular imaging and the development of anti-thrombotic and anti-inflammatory therapies.

Other names

Annexin VLipocortin VEndonexin IICalphobindin IPlacental anticoagulant protein 4PAP-IVThromboplastin inhibitorVascular anticoagulant-alpha

Annexin A5 binds to phosphatidylserine (PS) on cell membranes in a calcium-dependent manner, which sterically inhibits the binding of coagulation factors (Factors Xa and Va), thus preventing the formation of the prothrombinase complex [Source: PubMed, 15134468]. In the context of Annexin A1, the protein binds to the Formyl Peptide Receptor 2 (FPR2) to trigger pro-resolving signaling pathways in leukocytes, reducing inflammation [Source: PubMed, 21844396].