Development of phospholipid synthesizing enzymes in castor bean endosperm

Bowden, Linda; Lord, J. Michael

doi:10.1016/0014-5793(75)80787-3

Cited by 39 publications

(33 citation statements)

References 7 publications

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“…The production of these new organelles requires the prior synthesis of membrane constituents, namely protein and phospholipids. Synthesis of the protein most likely occurs by the reassembly ofamino acids from degraded protein bodies, while synthesis of most of the phospholipids (2,13,(17)(18)(19)27) takes place in the ER, beginning with phosphatidic acid synthesis by reaction of glycerol-3-P with fatty acyl-CoA thioesters. Donaldson and Beevers (5) studied the fatty acid composition of phospholipids in the developing organelles of endosperm of germinating castor bean seeds, and showed that the familiar components, palmitic, stearic, oleic, linoleic, and linolenic acids, comprise the membrane fatty acids; ricinoleic, the predominant storage fatty acid, is not present in membranes.…”

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confidence: 99%

“…Acetyl-CoA carboxylase was assayed by the same method as for RuDP carboxylase, except that the reaction mixture contained 120 mM Tris (pH 7.5), 150 mM MgCl2, 1 mM acetyl-CoA prepared according to Ochoa (21), 50 mim NaH'4CO3 (0.04 mCi/mmol), 2 mM ATP, and 0.1 ml of enzyme in a fmal volume of 0.5 ml.…”

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confidence: 99%

“…The fatty acids are transported out of the plastids to the ER where they are activated to acyl-CoA thioesters by a thiokinase enzyme (32). An acyltransferase enzyme in the ER (27) catalyzes the esterification of the acyl-CoA thioesters to glycerol-3-P to form phosphatidic acid, which is subsequently converted by enzymes in the ER (2,13,17,18,19) to all of the other membrane phospholipids. Oleate is most likely further desaturated in the ER (4), but whether the substrate for desaturation is oleoyl-CoA (29) or a,R-oleoyl phospholipid (9) is a subject of current discussion.…”

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Fatty Acid Synthesis in Endosperm of Young Castor Bean Seedlings

Vick¹,

Beevers²

1978

Plant Physiol.

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In the endosperm of ungerminated castor bean seeds, glyoxysomes and mitochondria are barely detectable, but their numbers increase dramatically during the first 5 days of growth (28). The production of these new organelles requires the prior synthesis of membrane constituents, namely protein and phospholipids. Synthesis of the protein most likely occurs by the reassembly ofamino acids from degraded protein bodies, while synthesis of most of the phospholipids (2,13,(17)(18)(19) 27) takes place in the ER, beginning with phosphatidic acid synthesis by reaction of glycerol-3-P with fatty acyl-CoA thioesters. Donaldson and Beevers (5) studied the fatty acid composition of phospholipids in the developing organelles of endosperm of germinating castor bean seeds, and showed that the familiar components, palmitic, stearic, oleic, linoleic, and linolenic acids, comprise the membrane fatty acids; ricinoleic, the predominant storage fatty acid, is not present in membranes. Acetate incorporation studies in vivo show that the membrane lipids are synthesized de novo rather than from storage lipid (4).

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Fatty Acid Synthesis in Endosperm of Young Castor Bean Seedlings

Vick¹,

Beevers²

1978

Plant Physiol.

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“…Phosphatidycholine and phosphatidylethanolamine are the major constitutents of the total phospholipid in the glyoxysomal membrane (Donaldson, Tolbert and Schnarrenberger, 1972) and in castor bean endosperm maximal activity of the phosphatidylcholine synthesizing enzyme preceeds the peak in cellular content of glyoxysomes consistent with membrane constituents being available for organelle assembly (Bowden and Lord, 1975). Similarly, in dark-grown pumpkin cotyledons phosphorylcholine glyceride transferase activity was maximal in 4-to 5-day old seedlings and preceeded the maximal development of glyoxysomes (Fig.…”

Section: Development Of Phosphatidycholine Synthesizing Enzymementioning

confidence: 86%

Density Labelling During Microbody Development in Cotyledons

Brown

Merrett

1977

New Phytologist

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SUMMARYDuring the development of pumpkin {Cucurbita pepo) cotyledons peroxisomal development was dissociated completely from glyoxysomal decline by keeping seedlings in darkness for up to 20 days; gly collate oxidase activity resulting from illumination then occurred after complete decay of isocitrate lyase. During cotyledon development a peak of phosphorylcholine glyceride transferase activity preceded maximal development of glyoxysomes while a second peak of activity occurred after illumination but before maximal development of peroxisomes. When dark-grown cotyledons were illuminated on transfer to ^H20 and microbodies isolated by gradient centrifugation, peroxisomes were separated from glyoxysomes because of their greater equilibrium density. The observed density shift for peroxisomes suggests that they arise by de novo synthesis rather than by modification of glyoxysomes.

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“…56-591. Dr J. M. Lord (University of Bradford), a proponent of the latter view, presented work showing that the enzymes of phospholipid synthesis in castor-bean endosperm are located in the endoplasmic reticulum [59]. The protein composition of purified glyoxysomal membranes, as determined by SDS-polyacrylamide gel electrophoresis, is very similar to that of the endoplasmic reticulum.…”

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confidence: 99%