A2 Biology Light Dependant Reaction Electron Transport Chain question?

At two points in the chain, protons are pumped into the thylakoid lumen. Firstly, when the oxygen-evolving complex lyses water and secondly when plastoquinone (a hydrogen carrier) transfers an electron to plastocyanin (an electron carrier) via the cytochrome b6f complex. These events build up an electrochemical gradient of protons across the membrane, which ATP synthase harnesses to produce ATP from ADP and Pi.