Fig. 2: SDS-PAGE analysis and identification of phosphorylation state of proteins in the PSI-LHCI-LHCII supercomplex purified from C. reinhardtii cells in state 2.

a SDS-PAGE analysis of the PSI-LHCI and PSI-LHCI-LHCII purified from C. reinhardtii cells locked in state 2. The proteins of the Coomassie bands was identified based on the mass spectrometry analysis. In the band of Type I LHCBM, the amount of LHCBM4 is relatively lower than that of LHCBM3, but higher than that of LHCBM8. b Immunoblot analysis of the phosphoproteins in PSI-LHCI-LHCII supercomplex using a phosphothreonine antibody. The polypeptide samples were separated by SDS-PAGE and stained with Coomassie blue (left), and polypeptides in the gels were electrophoretically transferred to a nitrocellulose membrane and proteins were detected with a PThr antibody (right). c Detection of the phosphoproteins by Pro-Q Diamond staining. The polypeptide samples were separated by SDS-PAGE and stained with Coomassie blue (left), and then the same gel was stained with Pro-Q Diamond to detect the presence of phosphoproteins (right). Lane 1: marker; lane 2: thylakoid membranes; lane 3: PSI-LHCI after size-exclusion chromatography; lane 4: PSI-LHCI-LHCII after size-exclusion chromatography. Samples were loaded onto SDS-PAGE at 20, 5, and 5 μg of Chl per lane in a, b, and c, respectively. The SDS-PAGE and immunoblot analysis were conducted more than three times with samples independently purified, and all results are similar to the ones shown here.