So within the matrix of the mitochondria, we essentially generate these ATP molecules. And that means we use up the ADP molecules. So we want to actually move the ATP out of the matrix while at the same time we want to bring ADP from the cytoplasm into the matrix. So at the same time that the ATP moves out of the matrix into the cytoplasm, the ADP is brought from the cytoplasm and into the matrix so that oxidative asphorylation of the ADP can take place along the electron transport chain found on the inner membrane of the mitochondria. Now, before we actually take a look at the mechanism by which ATP ADP translocase actually functions, let's discuss what the structure of ATP ADP translocase actually is. Well, this is a homodymer molecule and what that means is it consists of two identical polypeptide chains and each one of these identical polypeptide chains consist of six alpha helices that span the membrane.