FITC-Annexin V and PI Apoptosis Kit

The FITC and PI Apoptosis Kit provides a convenient method for quantifying apoptotic (green) and necrotic (red) cells within the same cell population by flow cytometry or fluorescence microscopy. Fluorescent conjugates of Annexin V can be used to label apoptotic cells. The human anticoagulant Annexin V is a 35-36 kilodalton, Ca 2+ -dependent phospholipid-binding protein with high affinity for phosphatidylserine (PS) . In normal viable cells, PS is located on the inner leaflet of the cytoplasmic membrane. However, in apoptotic cells, PS is translocated from the inner to the outer leaflet of the plasma membrane, where it is available for binding to fluorescently labeled Annexin V, which can be detected byfluorescence microscopy or flow cytometry. Propidium iodide (PI) is a membrane impermeant DNA- binding dye that is commonly used to selectively stain dead cells in a cell population. PI is excluded by live cells and early apoptotic cells, but stains necrotic and late apoptotic cells with compromised membrane integrity. PI can be excited by the 488, 532, or 546 nm laser lines, and emits red fluorescence.