The CF0-CF1 complex is the ATP synthase complex of the chloroplast that functions similarly to the F0F1 complex of mitochondria. It is located in the thylakoid membranes, as shown in Figure 17.15. During photosynthesis, electrons are pumped into the thylakoid lumen from the stroma, forming a proton gradient. Movement of the protons out of the thylakoid lumen through the CF0-CF1 complex back to the stroma provides the driving force for photophosphorylation, the process of making ATP in photosynthesis. A similar mechanism is responsible for ATP synthesis in oxidative phosphorylation.