Identification of photosynthetic subunits copurified with His-tagged PSBS using immunoblotting. Solubilized thylakoids and eluates after affinity chromatography from psbs KO, N-His-PSBS, and C-His-PSBS were compared using antibodies recognizing different subunits of the photosynthetic apparatus, LHCII, LHCB4, CP47, and PSAA. A total of 0.35 µg of Chl starting solubilized thylakoids was loaded for α-LHCII, α-CP47, and α-PSAA, and 0.12 µg of Chl was loaded for α-LHCB4. For chromatography eluates, a volume equivalent to purification from 100 µg of Chl starting thylakoids was loaded.