Figure 4.

Accumulation of photosynthetic complexes and antenna proteins, as quantified by immunoblot analyses using antibodies against essential subunits of the different photosynthetic complexes (A) and representative antenna proteins of PSII and PSI (B). A, Samples were loaded on an equal chlorophyll basis, and for semiquantitative analysis, 200%, 150%, and 100% of the wild-type sample (WT) were loaded in lanes 1 to 3 for comparison. For PSII, the essential PSII reaction center subunits PsbD (D2 protein) and PsbE, the extrinsic PsbO subunit of the oxygen-evolving complex, and the nonessential PsbS protein, which is required for photoprotective nonphotochemical quenching of excess excitation energy, were analyzed. Cytochrome b₆f complex accumulation was probed with antibodies against cytochrome f (PetA) and the Rieske iron-sulfur protein (PetC). PSI accumulation was probed with antibodies against the essential PsaA and PsaB reaction center subunits. ATP synthase abundance was probed with an antibody against the essential AtpB subunit. B, To determine LHC protein accumulation, a dilution series of 25%, 50%, and 100% of the wild-type sample was loaded in lanes 1 to 3 for semiquantitative analysis. For the PSII antenna, accumulation of the Lhcb1 and Lhcb2 subunits was tested. For the PSI antenna, accumulation of Lhca1, Lhca2, and Lhca4 was determined.