Cooperative binding of Annexin A5 to phosphatidylserine on apoptotic cell membranes
| Autor: | Christine Schorn, Ricardo A. Chaurio, Christina Janko, Luis E. Muñoz, Ivica Jeremic, Martin Herrmann, Mona H C Biermann |
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| Rok vydání: | 2013 |
| Předmět: |
Biophysics
Apoptosis Plasma protein binding Phosphatidylserines Biology Flow cytometry chemistry.chemical_compound Structural Biology Annexin medicine Humans Annexin A5 Molecular Biology Cells Cultured medicine.diagnostic_test Cell Membrane Cooperative binding Cell Biology Phosphatidylserine Flow Cytometry Cell biology Membrane chemistry Fluorescein-5-isothiocyanate Protein Binding |
| Zdroj: | Physical biology. 10(6) |
| ISSN: | 1478-3975 |
| Popis: | Healthy cells exhibit an asymmetric plasma membrane with phosphatidylserine (PS) located on the cytoplasmic leaflet of the plasma membrane bilayer. Annexin A5-FITC, a PS binding protein, is commonly used to evaluate apoptosis in flow cytometry. PS exposed by apoptotic cells serves as a major 'eat-me' signal for phagocytes. Although exposition of PS has been observed after alternative stimuli, no clearance of viable, PS exposing cells has been detected. Thus, besides PS exposure, membranes of viable and apoptotic cells might exhibit specific characteristics. Here, we show that Annexin A5 binds in a cooperative manner to different types of dead cells. Shrunken apoptotic cells thereby showed the highest Hill coefficient values. Contrarily, parafomaldehyde fixation of apoptotic cells completely abrogates the cooperativity effect seen with dead and dying cells. We tend to speculate that the cooperative binding of Annexin A5 to the membranes of apoptotic cells reflects higher fluidity of the exposed membranes facilitating PS clustering. |
| Databáze: | OpenAIRE |
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