Annexin V Detection Kits

In the early stages of apoptosis, changes can be observed on the cell surface: Cells lose their phospholipid membrane asymmetry and expose phosphatidylserine (PS) on the exterior plasma membrane. Annexin V is a Ca2+-dependent, phospholipid-binding protein with high affinity for phosphatidylserine (PS) and is thus very useful for identifying apoptotic cells exposing PS on the cell surface to the extracellular environment. Annexin V may be conjugated to biotin or fluorophores such as FITC and phycoerythrin (PE) or it may be tagged with EGFP (Enhanced Green Fluorescent Protein). Since Annexin V conjugates or tagged Annexins retain their high affinity for PS, they are ideally suited as highly sensitive probes to identify early apoptotic cells and to detect apoptosis much earlier than assays based on DNA fragmentation or loss of membrane integrity. The stained cells can be evaluated by flow cytometry or fluorescence microscopy using common filter sets and flow cytometer channels.