Annexin V-FITC/PI Apoptosis Detection Kit Annexin V-FITC/PI

The Annexin V-FITC/PI Cell Apoptosis Detection Kit uses FITC-labeled Annexin V as a fluorescence probe to detect the onset of early apoptosis.

The Annexin V-FITC/PI Cell Apoptosis Detection Kit is designed to detect early apoptosis using FITC-labeled Annexin V as a probe. In normal viable cells, phosphatidylserine (PS) is located on the inner leaflet of the cell membrane. During early apoptosis, PS is translocated to the outer leaflet and becomes exposed to the extracellular environment. Annexin V is a 35–36 kDa Ca²⁺-dependent phospholipid-binding protein with high affinity for PS, allowing it to selectively bind to early apoptotic cells.

The kit also includes propidium iodide (PI) to distinguish viable and early apoptotic cells from late apoptotic or necrotic cells. PI is a nucleic acid dye that cannot penetrate intact cell membranes but can enter cells with compromised membranes, staining their nuclei red. When used together, live cells remain Annexin V⁻/PI⁻, early apoptotic cells are Annexin V⁺/PI⁻, and late apoptotic or necrotic cells show double-positive staining (Annexin V⁺/PI⁺).