English: Schematic drawing of the 3D structure of the photosynthetic reaction center[1] from Rhodopseudomonas viridis. The membrane is shown as pale yellow, bacteriochlorophylls are green, hemes in the cytochrome are red, and transmembrane alpha-helices are gold cylinders. This was the first crystal structure of a membrane protein, earning a Nobel Prize in 1988. Coordinates from PDB: 1PRC​; drawn by Jane Richardson, scanned and touched up by David Richardson.