Distribution of characteristic membrane proteins in granum and stroma thylakoids

Membrane fractions obtained by ultrasonication of Vicia faba thylakoids were analyzed by sodium dodecyl sulphate gel electrophoresis. The polypeptide patterns revealed a six-times-higher ratio of the apoprotein (1) of P700 chlorophyll a protein to the apoprotein (2) of one of the chlorophyll a proteins in photosystem II in the light (stroma) fraction as compared with the heavy (grana) fraction indicating different distribution of the two photosystems. Additionally, the light fraction was clearly depleted in chlorophyll a/b apoproteins 2a and 2b of the light-harvesting complex and enriched in CF1 alpha and beta subunits. In contrast to the fairly constant ratio of the CF1 subunits the ratio of chlorophyll a/b apoprotein 2a/2b differed significantly between the light and heavy fraction suggesting a different composition for light-harvesting complex in stroma and grana regions of the thylakoids.