Characterization of Photosystem I Super Complexes Induced by State Transitions Using Stable Isotope Labeling and Phosphopeptide Isolation

摘要

The combination of sucrose density gradient centrifugation, stable isotope labeling is a convenient method for mass spectrometry based quantification of membrane complexes. Excellent coverage of the photosynthetic membrane complexes was achieved. Novel phosphorylation sites were determined. Three PSII subunits were found to co-fractionate with PSI during S2. The phosphorylation sites in the LHCB proteins are conserved. All but two of the LHCB4 are phosphorylated at the N-terminus of the mature protein. LHCB4.3 lacks the conserved phosphorylation sites and is not likely to be involved in state transitions. Additional biological replicates are needed.