EPR STUDY OF ANNEXIN V-CARDIOLIPIN CA-MEDIATED INTERACTION IN PHOSPHOLIPID-VESICLES AND ISOLATED-MITOCHONDRIA

The properties of the binding of annexin V to variously composed phosp holipid vesicles have been studied by applying a recently developed EP R method, using an annexin V spin label. By this approach, this protei n is seen to bind to acidic phospholipid-containing vesicles, as repor ted, thus confirming the reliability of the method. In addition, bindi ng of this annexin to cardiolipin-containing vesicles has been studied in more depth, and the protein has been shown to have a distinct affi nity for this phospholipid. As a cardiolipin-rich natural membrane sys tem, mitochondrial membranes and mitoplasts from rat liver were consid ered, and a strong binding of AV to these membranes was observed. Havi ng compared this binding with that to phospholipid vesicles, cardiolip in-rich microdomains in the mitochondrial membranes are proposed as th e putative mitochondrial binding sites for annexin V.