They're water soluble, and so they do not actually need any type of protein to move them to the target cell. So we see that ketone bodies are water soluble, and they can move inside the blood without being transported by proteins such as albumin. Now, the ultimate goal of these ketone bodies when they arrive in the target cell is to transform those ketone bodies back into acetyl coenzyme A, because now in the target cell, we're going to use that acetyl coenzyme A combined with oxalo acetate to help us generate those ATP molecules. So in the case of d three hydroxybutyrate, that is transformed back into acetyl acetate by the activity of this enzyme. But now we use an NAD plus to form NADH, which is the opposite of this step here. If we have aceto acetate going into the target cell, that simply enters directly in this stage, and the acetyl acetate is transformed into acetoacy acetoacetal coenzyme A, and that is catalyzed by the enzyme COA transferase.