Distribution of Characteristic Membrane Proteins in Granum and Stroma Thylakoids

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Abstract
Membrane fractions obtained by ultrasonication of Vicia faba thylakoids were analyzed by sodium dodecyl sulfate gel electrophoresis. The polypeptide patterns revealed a 6-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 2 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 [coupling factor 1] .alpha. and .beta. subunits. In contrast of 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.