Abstract
Light-harvesting chlorophyll a/b complex I (LHCI) is antenna complex associated with photosystem I (PSI) core complex. In higher plants, six LHCI distinctive polypeptides are found and four out of six were identified in crystal structure of PSI-LHCI supercomplex. In contrast, Chlamydomonas reinhardtii contains nine distinctive LHCI subunits that were all copurified with PSI-LHCI supercomplex. However, the copy number and arrangement of LHCI in PSI-LHCI supercomplex have not yet been determined. Here we report quantitative estimation of stoichiometry of LHCI subunits in PSI-LHCI supercomplex. The polypeptides that are similar in size were separated by optimized SDS-PAGE systems and were stained with fluorescence dye, FLAMINGO. Intensity of polypeptides was measured by scanning the stained gel and the amount was estimated by calculating the area of the signal, assuming that the signal intensity is proportional to the molecular mass. We will also discuss structure and arrangement of LHCIs in PSI-LHCI supercomplex.
