What do the proteins in thylakoids do?

Answer 1

Resembling to mitochondria, chloroplasts carry out their energy interconversions by chemiosmotic mechanisms in much the same way as the mitochondria do. The inner membrane surrounds a large space called stroma (analogous to the mitochondrial matrix) and contains various enzymes, ribosomes, RNA, and DNA. This inner membrane is not folded into cristae (as it is in mitochondria) and does not contain an electron-transport chain, instead, the electron-transport chain as well as the photosynthetic light-absorbing system and an ATP synthase are all contained in a third distinct membrane that forms a set of flattened disclike sacs, the thylacoids. The lumen of each thylacoid is though to be connected with the lumen of other thylacoid, thereby defining a third internal compartment called the thylacoid space, which is separated from the stroma by the thylacoid membrane.

All this energy engineering of the plants, allows that the knobbed end of the chloroplast ATP synthase, where ATP is synthesized, protrude from the thylacoid membrane into the stroma, just as it protrudes into the matrix from the membrane of each mitochondrial crista.