Prenyllipid synthesis

When etioplasts from the cotyledons of these seedlings are incubated in tbe presence of C-14 intermediates of the IPP pathway no prenyllipid synthesis can be observed, whereas IPP itself is well incorporated (Table 1). In the presence of cytoplasmic supernatant, however, which contains all the enzymes necessary for IPP formation the intermediates are also well incorporated. 

Table 1. Sinapis cotyledon etioplasts. Prenyllipid synthesis from C-14 precursors in the absence and presence of cytoplasmic supernatant (CS). Chi, chlorophylls car, carotenes. From Lutke-Brinkhaus and Kleinig, in press.

Lichtenthaler, H.K. 1982. Synthesis of prenyllipids in vascular plants (including chlorophylls, carotenoids, prenylquinones). In CRC Handbook of Biosolar Resrouces, Vol. I, part I Basic Principles (A. Matsui and C.C. Black, eds.) pp. 405-421. CRC Press, Boca Raton, Fla. 

The formation of IPP proceeds according tg the relatively well established scheme shown in Fig. 1, ultimately from acetyl-CoA. There are three sites or compartments in the plant cell lAihere prenyllipids are synthesized (i) the endoplasmic reticulum (ER) for sterol formation (ii) the piastids for the synthesis of the side chains of chlorophylls, quinones and tocopherols, and of the carotenoids and fatty acid prenyl esters (iii) the mitochondria for the synthesis of the ubiquinone side chains. Therefore, the question arises whether there are also three cellular sites for IPP formation, whereby the cytopiasm/ER is uncontested. ... 

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