Western blot of Puc2BA-PhoA fusion proteins from cells of R. sphaeroides 2.4.1 and mutants of this strain. (A) Western blot of cells of mutant ΔPUC2BA carrying plasmids pUC2P-PhoA (2P-PhoA), pUC2B-PhoA/pRK415 (2B-PhoA), pUC2AS-PhoA/pRK415 (2AS-PhoA), and pUC2A-PhoA/pRK415 (2A-PhoA) grown anaerobically at different light intensities. (B) Western blot of cells of R. sphaeroides 2.4.1, mutant ΔPUC1BA, and mutant ΔPUC-C carrying plasmids pUC2B-PhoA/pRK415, pUC2AS-PhoA/pRK415, and pUC2A-PhoA/pRK415 grown anaerobically at 100 W/m2. Fifty micrograms of protein from each cell extract was applied to an SDS-PAGE gel, and anti-PhoA antibody was used to detect the PhoA fusion protein. The sizes of the hybrid proteins are indicated on the right. Cells were grown to an OD600 of 0.3 to 0.4.