Phosphatidylethanolamine Synthesis in Castor Bean Endosperm

Sparace, Salvatore A.; Wagner, Leslie K.; Moore, Thomas

doi:10.1104/pp.67.5.922

Cited by 27 publications

(21 citation statements)

References 24 publications

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“…In higher plants, however, the question of whether a single or separate enzyme(s) catalyzes the respective reactions remains unanswered. Several studies in plants have presented compelling evidence suggesting that the same enzyme catalyzes both reactions (Macher and Mudd, 1974;Lord, 1975;Sparace et al, 1981;Justin et al, 1985). The strongest data supporting this hypothesis are observations that CDP-choline and CDP-ethanolamine are competitive inhibitors of ethanolaminephosphotransferase and cholinephosphotransferase activities, respectively, and the failure to find inhibitors that can differentiate the two activities.…”

Section: Discussionmentioning

confidence: 99%

“…Severa1 studies have presented evidence suggesting that cholinephosphotransferase and ethanolaminephosphotransferase activities in higher plants may be catalyzed by a single enzyme (Macher and Mudd, 1974;Lord, 1975;Sparace et al, 1981;Justin et al, 1985). Among the data supporting this hypothesis are observations that CDP-choline and CDPethanolamine are competitive inhibitors of ethanolaminephosphotransferase and cholinephosphotransferase activities, respectively.…”

Section: Lnhibition Of Soybean Aaptt-mediated Cholinephosphotransferamentioning

confidence: 99%

“…Although it is clear that separate AAPTases are involved in PC and PE biosynthesis in animais and yeast (Bell and Coleman, 1980;Percy et al, 1984), severa1 studies have suggested that the same enzyme is utilized in the synthesis of both PC and PE in higher plants (Macher and Mudd, 1974;Lord, 1975;Sparace et al, 1981;Justin et al, 1985).…”

Section: Introductionmentioning

confidence: 99%

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The AAPT1 gene of soybean complements a cholinephosphotransferase-deficient mutant of yeast.

et al. 1994

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Section: Discussionmentioning

confidence: 99%

Section: Lnhibition Of Soybean Aaptt-mediated Cholinephosphotransferamentioning

confidence: 99%

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The AAPT1 gene of soybean complements a cholinephosphotransferase-deficient mutant of yeast.

et al. 1994

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“…Enzyme Assays CDP-ethanolamine: 1,2 diacylglycerol ethanolaminephosphotransferase was assayed as previously described (27). For the base exchange reactions, ethanolamine incorporation was measured in 200 mm Hepes buffer (pH 7.8), 2 mM CaC12, and 0.01 mm [2-'4C]ethanolamine hydrochloride (2.4 mCi/mmol) (26), while for serine incorporation 40 mM Hepes buffer (pH 7.8), 2 mm CaCl2, and 0.4 mm [3-'4C]L-serine (5 mCi/mmol) comprised the standard assay medium (20).…”

Section: Methodsmentioning

confidence: 99%

“…var Hale) endosperm, and synthesis by ethanolaminephosphotransferase utilizing CDP-ethanolamine was described earlier for this same organelle (27). Numerous hypotheses have been offered to explain the significance of two reactions to provide the same phospholipid, but none has proven completely satisfactory.…”

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confidence: 99%

Phosphatidylethanolamine Synthesis by Castor Bean Endosperm

Shin

Moore²

1990

Plant Physiol.

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The bilayer distribution of phosphatidylethanolamine (PtdEtn) in the endoplasmic reticulum of castor bean (Ricinus communis L. var Hale) endosperm following synthesis by both the CDPethanolamine: 1,2-diacylglycerol ethanolaminephosphotransferase and ethanolamine base exchange reactions have been studied. Two chemical probes, 1-fluoro-2,4-dinitrobenzene (FDNB) and 2,4,6-trinitrobenzenesulfonic acid (TNBS), which covalently bind to the free amino groups, were utilized. The endoplasmic reticulum membranes were impermeable to TNBS at 4 and 25°C, but were permeable to FDNB at both temperatures. FDNB treatment of the PtdEtn from the base exchange reacted with 92% of the PtdEtn, while 80% of the lipid reacted with TNBS. Thus, at least 80% of the PtdEtn synthesized by the base exchange reaction was localized in the outer leaflet of the membrane, with about 12% occurring on the inner leaflet and about 8% being inaccessible. For PtdEtn formed by the CDP-ethanolamine pathway, 85% reacted with FDNB and 70% with TNBS, indicating that at least 70% was produced to the cytoplasmic face of the ER and 15% to the lumen side. The remainder was inaccessible to the probes. The sensitivity to trypsin of the two reactions also was tested. The ethanolamine base exchange enzyme, as well as that for L-serine exchange, retained activity following exposure to trypsin, but the activity of ethanolaminephosphotransferase disappeared after such treatment. This indicates that both base exchange enzymes are exposed to the lumenal side of the ER, while CDP-ethanolamine: 1,2-diacylglycerol ethanolaminephosphotransferase is exposed on the outer or cytoplasmic side. These results are discussed with respect to the final phospholipid distributions and the presumed sources of the water-soluble substrates.In an accompanying paper (26), we demonstrated synthesis of PtdEtn2 by an ethanolamine exchange reaction in the endoplasmic reticulum of castor bean (Ricinus communis L.

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The Plant Endoplasmic Reticulum

Persson

Harper

2006

Plant Cell Monographs

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PrefaceThe endoplasmic reticulum (ER) is the mother of all membranes. Essentially all other membranes, except those of plastids and mitochondria, are derived from it through vesicle-mediated membrane trafficking. It serves, therefore, as the port of entry into the endomembrane system for proteins destined to reach the vacuole or the cell wall. Quality control machinery in the ER lumen presides over the export competence of these proteins, and coupled to selective sorting mechanisms for their entry into export vesicles, this elevates this organelle to the most important regulator of protein movement along the secretory pathway. Moreover, its functions can be upregulated during various stages of plant development, e.g., during storage protein deposition in seed maturation, or in answer to stress, e.g., the production of pathogen-related proteins, and the so-called unfolded protein response.In addition to its function in the synthesis of luminal and integral membrane proteins, the ER is also the site of structural and storage lipids. Further important features of the ER are its role in the homeostasis of cellular calcium and -through the localisation of cytochrome P450 enzymes -in the synthesis of a number of plant hormones. These manifold activities are reflected in the great plasticity of the ER as a structure, with over a dozen specialized domains recognized for this organelle.To my knowledge, a book devoted to the ER in plants has never been published; indeed, I am not aware of a similar book on this organelle existing for the animal field. There have been a couple of excellent reviews on the ER of plant cells (one by Vitale and Denecke in The Plant Cell and one by Staehelin in The Plant Journal), but these lie several years back and were, of necessity, somewhat limited in scope. Therefore, I think it is both timely and appropriate to put the spotlight onto the ER as a whole, especially since GFP technology has provided news ways of looking at the dynamics of this membrane, and its relationship to other organelles, especially the Golgi apparatus and peroxisomes.

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Phosphatidylethanolamine Synthesis in Castor Bean Endosperm

Cited by 27 publications

References 24 publications

The AAPT1 gene of soybean complements a cholinephosphotransferase-deficient mutant of yeast.

The AAPT1 gene of soybean complements a cholinephosphotransferase-deficient mutant of yeast.

Phosphatidylethanolamine Synthesis by Castor Bean Endosperm

The Plant Endoplasmic Reticulum

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