Annexin V-FITC/PI Apoptosis Detection Kit

In normal cells, phosphatidylserine (PS) is only distributed inside the lipid bilayer of the cell membrane. In the early stage of apoptosis, the phosphatidylserine (PS) in the cell membrane turns from the inside of the lipid membrane to the outside. Annexin V is A Ca2+-dependent phospholipid binding protein with a molecular weight of 35-36 kDa, has a high affinity for phosphatidylserine, so Annexin V is recognized as one of the sensitive indicators for detecting early cell apoptosis.
The Annexin V is labeled with green fluorescence (FITC), and the labeled Annexin V is used as a probe to detect the occurrence of cell apoptosis using a fluorescence microscope or flow cytometer. Propidium Iodide (PI) is a nucleic acid dye. It cannot penetrate the complete cell membrane of normal cells or early apoptotic cells. However, for cells in the middle and late stages of apoptosis and necrotic cells, PI can penetrate the cell membrane. The nucleus is stained red. Therefore, matching Annexin V and PI can distinguish cells in different stages of apoptosis.