Evidence for the presence and location of annexins in human platelets

In this study the identity of annexins in human platelets has been determined together with their ability to be released by agents which induce platelet degranulation. The presence of proteins cross-reacting to antibodies against annexins I and V was detected in human platelets. However, the study provided evidence that these annexins are not located on the surface of the plasma membrane in a Ca++ dependent manner. Moreover, activation of platelets with several agents which induced platelet degranulation did not cause release of annexins I or V as determined by both immunoblotting and ELISA.