Description: Annexins are a family of calcium-dependent phospholipid-binding proteins, which bind to phosphatidylserine (PS) to identify apoptotic cells. In healthy cells, PS is predominantly located along the cytosolic side of the plasma membrane. Upon initiation of apoptosis, PS loses its asymmetric distribution in the phospholipid bilayer and translocates to the extracellular membrane, which is detectable with fluorescently labeled Annexin V. In early stages of apoptosis, the plasma membrane excludes viability dyes such as propidium iodide (PI) and 7-AAD, therefore cells which display only Annexin V staining (PI/7-AAD negative) are in early stages of apoptosis. During late-stage apoptosis, loss of cell membrane integrity allows Annexin V binding to cytosolic PS, as well as cell uptake of PI and 7-AAD. Annexin V staining, paired with 7-AAD or PI is widely used to identify apoptotic stages by flow cytometry.
Annexin V has also been identified as an anticoagulant protein in the blood coagulation cascade, by acting as an inhibitor of prothrombin activation. The presence of antibodies to Annexin V is associated with systemic lupus erythematosus (SLE), recurrent spontaneous abortions and systemic sclerosis (SSc).
Purity: Annexin V is >89% pure as demonstrated by SDS-gel electrophoresis and reverse phase HPLC.
Biotin labelling allows simple direct detection of PS by FACS analysis using fluorescence-labeled Streptavidin. Counterstaining by propidium iodide allows the discrimination of apoptotic cells.
The protein encoded by this gene belongs to the annexin family of calcium-dependent phospholipid binding proteins some of which have been implicated in membrane-related events along exocytotic and endocytotic pathways. Annexin 5 is a phospholipase A2 and protein kinase C inhibitory protein with calcium channel activity and a potential role in cellular signal transduction, inflammation, growth and differentiation. Annexin 5 has also been described as placental anticoagulant protein I, vascular anticoagulant-alpha, endonexin II, lipocortin V, placental protein 4 and anchorin CII. The gene spans 29 kb containing 13 exons, and encodes a single transcript of approximately 1.6 kb and a protein product with a molecular weight of about 35 kDa.
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Protein Aliases: Anchorin CII; annexin 5; Annexin A5; Annexin V; Annexin-5; Calphobindin I; CBP-I; Endonexin II; epididymis secretory protein Li 7; Lipocortin V; PAP-I; Placental anticoagulant protein 4; Placental anticoagulant protein I; PP4; Thromboplastin inhibitor; VAC-alpha; Vascular anticoagulant-alpha
Gene Aliases: ANX5; ANXA5; ENX2; HEL-S-7; LC5; PP4; R74653; RPRGL3