A Comparison between Prolamellar Bodies and Prothylakoid Membranes of Etioplasts of Dark-Grown Wheat Concerning Lipid and Polypeptide Composition

The aim of the present investigation was to find factors critical for the co-existence of prolamellar bodies and prothylakoids in etioplasts of wheat (Triticum aestivum L. cv Starke II). The lipid composition of the prolamellar body and prothylakoid fractions was qualitatively similar. However, the molar ratio of monogalactosyl diacylglycerol to digalactosyl diacylglycerol was higher in the prolamellar body fraction (1.6 +/- 0.1), as was the lipid content on a protein basis. Protochlorophyllide was present in both fractions. The dominating protein of the prolamellar body fraction was protochlorophyllide oxidoreductase. This protein was present also in prothylakoid fractions. The other major protein of the prothylakoid fraction was the coupling factor 1, subunit of the chloroplast ATPase. From the lipid and protein data, we conclude that prolamellar bodies are formed when monogalactosyl diacylglycerol is present in larger amounts than can be stabilized into planar bilayer prothylakoid membranes by lamellar lipids or proteins.