Isolation of disaturated phosphatidylcholine with osmium tetroxide

Publisher Summary This chapter discusses the metabolism of molecular species of diacylglycerophospholipids. The glycerolipid composition of cell membranes and lipoproteins is metabolically adjusted to meet specific requirements, and it does not merely reflect the supply of different fatty acids in the diet or in the cell culture medium. However, adequate adjustment cannot always be possible, and under such conditions, the cellular activity can take place in a suboptimal physicochemical environment and characteristic symptoms of a disease state can appear. As the cellular lipid composition is subject to considerable dietary and pharmacological manipulation, there can be therapeutic alterations in the composition of the molecular species of the tissues and other animal species. The metabolism of the molecular species of the glycerophospholipids is intimately involved with the activity of the acyl transferases. Therapeutic alterations in the composition of the molecular species of the glycerolipids can be feasible and can yield beneficial results in the treatment of membrane diseases.

Metabolism of molecular species of diacylglycerophospholipids.

A quantitative time study of the incorporation of choline-3H, leucine-3H and galactose-3H in lung epithelial cells, was undertaken in vivo with electron microscopic autoradiography. Type II pneumocytes were selectively labeled with choline-3H, a specific precursor of phosphatidylcholine, which is the main component of pulmonary surfactant. Choline was initially localized in endoplasmic reticulum, then was rapidly transferred through the Golgi complex and stored in lamellar bodies. Previously undescribed small lamellar bodies are suggested as phospholipid carriers between Golgi complex and lamellar bodies. After initial incorporation in the endoplasmic reticulum, the leucine label migrated through the Golgi complex into lamellar bodies by fusion of multivesicular bodies, which are the carriers between the two structures. Galactose was modestly incorporated into lamellar bodies via the Golgi complex. Intra-alveolar myelin figures, recognized as excreted surfactant, were labeled 120 minutes after injection with the three precursors.



These findings indicate that the synthesis of a secretory product by type II pneumocytes involves phospholipid, protein and polysaccharide precursors; the secretory product is segregated as lamellar bodies which are destined to be excreted into the alveolar cavity to become part of the lining layer.

In vivo incorporation of choline- 3 H, leucine- 3 H and galactose- 3 H in alveolar type II pneumocytes in relation to surfactant synthesis. A quantitative radoautographic study in mouse by electron microscopy.

The Ca2+-dependent biosynthesis of lecithin, phosphatidylethanolamine and phosphatidylserine in rat liver subcellular particles

https://dspace.library.uu.nl/bitstream/handle/1874/17843/vereyken_72_somestudiesbiosynthesis.pdf;sequence=1

Some studies on the biosynthesis of the molecular species of phosphatidylcholine from rat lung and phosphatidylcholine and phosphatidylethanolamine from rat liver.

J.R. Norman

Papers

The incorporation of L-[Me-14C]methionine and [Me-3H]choline into lung phosphatides.

In vivo studies of [Me-3H]choline and [1,2-14C2]choline incorporation into lung and liver lecithins.