Absence of the NDH-H subunit in the ndhB− plastid transformants. Separation of protein fractions (20 mg of protein per lane) derived from purified chloroplasts by fully denaturating PAGE reveals no obvious difference after Coomassie Brilliant Blue staining between wild-type (WT) and ndhB− (1.2) tobacco plants. Western hybridization of the separated protein fractions electrotransferred onto nitrocellulose membranes by an anti-NDH-H antibody detects the protein in total thylakoid membranes and the stroma lamellae of the wild type. The absence of detectable NDH-H protein in the ndhB− mutant indicates that no functional NDH complex can be assembled. Molecular mass markers: 96, 66.2, 45, 31, 21.5, and 14.4 kD.