In normal cells, phosphatidylserine residues are found exclusively on the inner side of the cellular membrane. During apoptosis, phosphatidylserine is transported to the outer cell surface by scramblase proteins. This event acts as an "eat-me" signal for macrophages to dispose of the dying cell. When annotating to this term, curators should be aware of the following: 1) phosphatidylserine exposure on the cell surface can occur in circumstances other than apoptosis (for example, when blood platelets are activated, they expose phosphatidylserine to trigger the clotting system, see PMID:21107324). Do not annotate to GO:0070782 unless phosphatidylserine exposure is shown to be part of an apoptotic event. 2) Caution should be applied when a study quotes annexin V assays. The annexin A5 protein binds to phosphatidylserine-containing membrane surfaces, which are usually only present on the inner leaflet of the membrane. However, in cells undergoing apoptosis, phosphatidylserine becomes exposed on the outer leaflet of the membrane. A positive annexin assay can therefore be linked to apoptotic death, but it shouldn't be confused with molecular events strictly involved in the process of phosphatidylserine exposure.

midori

2009-07-02T02:41:44Z

biological_process

GO:0070782

• regulation of phosphatidylserine exposure on apoptotic cell surface

• positive regulation of phosphatidylserine exposure on apoptotic cell surface

• negative regulation of phosphatidylserine exposure on apoptotic cell surface