Immunogold localization of photosystems I and II in the green alga Chlamydomonas reinhardtii and the higher plant Pisum sativum : a comparative study

The distribution of Photosystems (PS) I and II was studied in the green alga Chlamydomonas reinhardtii and compared to that found in the higher plant Pisum sativum. Two antibodies were used; one, anti-CP1-e, was raised against the two reaction center proteins of PS I from Synechococcus elongatus, and the other, anti-CP40, was raised against the 40 kDa protein of PS II from the same organism. Immunogold labelling of C. reinhardtii sections showed that both appressed and non-appressed thylakoid membranes were labelled by each antiserum, with labelling on the non-appressed membranes being somewhat (1.7-1.8 times) higher than that on the appressed membranes.In P. sativum, anti-CP1-e labelling was 3.9 times higher on the non-appressed membranes than on the appressed ones, whereas anti-CP40 labelling was equally concentrated on both classes of membranes. The data show that PS distribution in C. reinhardtii is similar to that reported for other algae and different from that in higher plants