Annexin V is a marker of aEUR’
**Core Concept**
Annexin V is a protein that binds to phosphatidylserine (PS), a phospholipid component of cell membranes. Normally, PS is restricted to the inner leaflet of the cell membrane. However, during apoptosis, this asymmetry is disrupted, and PS is exposed on the outer leaflet, serving as a signal for phagocytic cells to remove dying cells.
**Why the Correct Answer is Right**
Annexin V specifically binds to PS, allowing it to detect and mark apoptotic cells. This property is exploited in various assays, including flow cytometry and fluorescence microscopy, to identify and quantify apoptotic cells. Annexin V binding is often used in conjunction with other markers, such as propidium iodide (PI), to distinguish between apoptotic and necrotic cells.
**Why Each Wrong Option is Incorrect**
**Option A:** Annexin V is not a marker of necrosis, as it specifically binds to PS, which is exposed during apoptosis, not necrosis.
**Option B:** Annexin V is not a marker of inflammation, although it may be used in conjunction with inflammatory markers in certain assays.
**Option C:** Annexin V is not a marker of cell proliferation, as it is primarily used to detect cell death.
**Clinical Pearl / High-Yield Fact**
Annexin V binding can be used to detect early stages of apoptosis, making it a useful tool in various research and clinical applications, including cancer diagnosis and treatment monitoring.
**Correct Answer:** B. apoptosis