And in a ptype Atpas, they basically use ATP molecules, they hydrolyze NATP molecules, they use that phosphoryl group to attach it onto that membrane protein, that pump. And then that creates a conformational change in the pump that allows the pump to actually move the molecule against the electrochemical grading as we'll see in just a moment. And one well studied pump that we're going to focus on, one well studied ptype Atpas will be the calcium Atpas that we're going to focus on in this lecture. And there are many other examples of ptype Atpas that we'll study in the future lecture. For instance, we're going to also look at the sodium potassium Atpas, which is also an example of a ptype Atpas. Now, where exactly do we find and what membrane do we find these calcium ATPases?