So far in our discussion of membrane pumps, we focus on pumps that utilize ATP molecules directly. So we focused on two types of ATPases. We discussed ptype Atpas, and we also discussed ABC transporter. So these are both Atpas, and what that means is they're membrane pumps that break down ATP molecules directly directly and use the energy that is stored within the chemical bonds of the ATP molecules to move other molecules and ions against their electrochemical gradients. Now, not all membrane pumps actually utilize ATP molecules directly. And membrane pumps that don't break down ATP directly yet are able to actually move molecules and ions against their electrochemical gradients are known as secondary transporters.