Synthesis of prenyl lipids in cells of spinach leaf. Compartmentation of enzymes for formation of isopentenyl diphosphate.
Purified spinach chloroplasts incorporate [1-14C]isopentenyl diphosphate into prenyl lipids in high yields. The immediate biosynthetic precursors of isopentenyl diphosphate (hydroxymethylglutaryl-CoA, mevalonate, mevalonate-5-phosphate, mevalonate-5-diphosphate), on the other hand, are not accepted as substrates and the corresponding enzymes hydroxymethylglutaryl-CoA reductase, mevalonate kinase, phosphomevalonate kinase, and diphosphomevalonate decarboxylase are not present in the organelles. These enzymes can only be detected in a membrane-bound form at the endoplasmic reticulum (hydroxymethylglutaryl-CoA reductase) and as soluble activities in the cytoplasm. The concept is developed that isopentenyl diphosphate is formed in the cytoplasm as a 'central intermediate' and is distributed then to other cellular compartments (endoplasmic reticulum, plastids, mitochondria) for further biosynthetic utilization.
D002451:Cell Compartmentation; D002736:Chloroplasts / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D045782:Hemiterpenes; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D008798:Mevalonic Acid / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000096:biosynthesis*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010944:Plants / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure
D045782:Hemiterpenes; D009943:Organophosphorus Compounds; C004809:isopentenyl pyrophosphate; D006903:Hydroxymethylglutaryl CoA Reductases; D009251:NADPH-Ferrihemoprotein Reductase; D010744:Phosphoric Monoester Hydrolases; D008798:Mevalonic Acid