Early in the apoptotic process, the characteristic cell surface phospholipid asymmetry is disrupted. This leads to the exposure of phosphatidylserine (PS) on the outer leaflet of the cell membrane. Annexin V is an anticoagulant protein that preferentially binds PS and, when conjugated to a reporter molecule, can be used as an indicator of apoptosis.
 |
| Schematic Representation of Apoptosis-Induced Membrane Changes Recognized by Annexin V. Reorganization of the plasma membrane occurs early in the apoptotic process disrupting phospholipid asymmetry and leading to the exposure of phophatidylserine on the outer leaflet of the cytoplasmic membrane. In the presence of calcium, Annexin V binds to phosphatidylserine allowing apoptotic cells to be easily identified by flow cytometry or fluorescence microscopy. |
The Annexin V conjugate may be used in Flow Cytometry or in other in situ detection methods to facilitate the rapid and early detection of cell surface changes associated with apoptosis. Annexin V binding to PS occurs only in dying cells, is calcium dependent, and reversible. Each Annexin V molecule binds approximately 50 exposed PS monomers.
TACS Annexin V – Fluorescein in situ
Label: Fluorescein
Testing Format: Flow Cytometry, Fluorescence Microscopy
Sample Type: Unfixed cells
Size: 100 Tests (Catalog # 4830-01-K), 250 Tests (Catalog # 4830-250-K)
 |
| Detection of Apoptotic Dexamethason-treated Thymocytes by Annexin V Staining. Thymocytes were left untrated (left) or treated with 100 nM dexamethasone for 15.5 hours (right) and then stained using Annexin V-FITC and propidium iodide provided in the Annexin V-FITC Apoptosis Detection Kit (Catalog # 4830-01-K). The combination of Annexin V-FITC and propidium iodide allows for the distinction between early apoptotic cells (Annexin V-FITC positive), late apoptotic and/or necrotic cells (Annexin V-FITC and propidium iodide positive), and viable cells (unstained). Analysis courtesy of Dr. C.M. Knudson, Howard Hughes Medical Institute, St. Louis, MO. |