Annexin V Assays

Annexin V assays are commonly used in apoptosis research to detect and quantify apoptotic cells. Annexin V is a calcium-dependent phospholipid-binding protein that has a high affinity for phosphatidylserine (PS), which is translocated from the inner to the outer leaflet of the plasma membrane during apoptosis. As a result, annexin V can be used to detect apoptotic cells based on their surface expression of PS.

Annexin V assays typically involve the use of fluorescently labeled annexin V, which binds to the PS on the surface of apoptotic cells. The cells are then analyzed using flow cytometry or fluorescence microscopy to detect the fluorescence signal. In addition to annexin V, propidium iodide (PI) is often used in these assays as a viability marker to distinguish between early apoptotic cells (annexin V-positive, PI-negative) and late apoptotic/necrotic cells (annexin V-positive, PI-positive).