Annexin V-FITC/PI Apoptosis Detection Kit

Phosphatidylserine is only found on the inner side of a normal cell's lipid bilayer. However, during the early stages of apoptosis, this membrane phosphatidylserine migrates to the outer side of the cell membrane before cell shrinkage, chromatin concentration, DNA fragmentation, and increased cell membrane permeability occur. Annexin V is a special protein that binds strongly to phosphatidylserine, which enables it to bind to the membrane of early apoptotic cells since phosphatidylserine is now exposed on the outside of the cell. This is why Annexin V is commonly used as a sensitive indicator for detecting early apoptotic cells. Propidium Iodide (PI) is a type of nucleic acid dye that cannot enter an intact cell membrane. However, once the middle and late apoptotic cells, as well as dead cells, exhibit increased membrane permeability, PI can penetrate these cells and make the nucleus appear red. To distinguish cells at different stages of apoptosis, Annexin V is often used in conjunction with PI.