Figure 5.
Membrane Attachment of the FNR/Tic62 Complexes Is Regulated by Light and Stromal pH.
(A) The amount of thylakoid-bound Tic62/FNR complexes is dependent on ambient growth light of the plants. Thylakoids were prepared from dark-adapted plants and compared with growth light (GL; 4 h under 100 μmol photons m−2 s−1) or high light (HL; 2 h under 1000 μmol photons m−2 s−1) treated samples. A BN-PAGE gel lane (5 to 13.5%) from wild-type and tic62 thylakoids with the major photosynthetic protein complexes indicated and immunoblots with αTic62 and αFNR antibodies are shown. The approximate position of BN size markers is indicated, and the HMW Tic62/FNR complexes are marked by an asterisk.
(B) The attachment of Tic62 and FNR to thylakoids is dependent on the stromal pH. Isolated pea thylakoids were mildly solubilized and incubated in sodium phosphate buffer with either pH 6.0, 7.0, or 8.0. After separation of soluble and membrane-bound proteins, pellets (P) and supernatants (S) were analyzed by immunoblotting with antibodies against Tic62 and FNR. A typical result of four independent experiments is shown. Furthermore, the amount of Tic62 and FNR in the pellet (gray) and supernatant (white) of all experiments (n = 4) was quantified (including se bars) and is depicted as fraction of total sample (100%).
[See online article for color version of this figure.]