Which platelet membrane phospholipid flips to the plasma surface on activation and serves as the assembly point for coagulation factors?

The correct response highlights the role of phosphatidylserine (PS) in the coagulation process. Under normal circumstances, phosphatidylserine resides on the inner leaflet of the platelet membrane. Upon platelet activation, for example during the formation of a clot, phosphatidylserine flips to the outer membrane surface.

This translocation is crucial because phosphatidylserine acts as a binding site for various coagulation factors, specifically those involved in the coagulation cascade, such as prothrombin. The exposure of phosphatidylserine creates an environment that facilitates the assembly of these factors, which is key to efficient thrombin generation and subsequent clot formation. Therefore, the exposure of phosphatidylserine on activated platelets is essential for proper hemostasis and the overall coagulation process.