Transport of lipids

The structure of cholic acid helps us understand how bile salts such as sodium tauro cholate promote the transport of lipids through a water rich environment The bot tom face of the molecule bears all of the polar groups and the top face is exclusively hydrocarbon like Bile salts emulsify fats by forming micelles m which the fats are on the inside and the bile salts are on the outside The hydrophobic face of the bile salt associates with the fat that is inside the micelle the hydrophilic face is m contact with water on the outside... 

LIPOPROTEINS. Blood plasma lipoproteins are prominent examples of the class of proteins conjugated with lipid. The plasma lipoproteins function primarily in the transport of lipids to sites of active membrane synthesis. Serum levels of low density lipoproteins (LDLs) are often used as a clinical index of susceptibility to vascular disease. 

We turn now to the biosynthesis of lipid structures. We begin with a discussion of the biosynthesis of fatty acids, stressing the basic pathways, additional means of elongation, mechanisms for the introduction of double bonds, and regulation of fatty acid synthesis. Sections then follow on the biosynthesis of glyc-erophospholipids, sphingolipids, eicosanoids, and cholesterol. The transport of lipids through the body in lipoprotein complexes is described, and the chapter closes with discussions of the biosynthesis of bile salts and steroid hormones. 

LBPs are likely to have conventional roles in the energy metabolism and transport of lipids in nematodes for membrane construction, etc. Many parasitic helminths have deficiencies in the synthesis of some lipids and so their lipid acquisition, transport and storage mechanisms clearly need to be specialized and therefore pertinent to the host-parasite relationship (Barrett, 1981). From a practical point of view, lipid transporter proteins may also be important in the delivery of anthelmintic drugs to their target most anthelmintics are hydrophobic and if they do not distribute to their site of action within the parasites by simple diffusion across and along membranes, then the parasite s own carrier proteins may be involved. 

Sorting and transport of lipids and proteins takes place during myelin assembly 68... 

The rationale for this type of contrast agent is to use the endogenous metabolic pathway of lipid metabolism in the liver for the transport of iodinated substances. Chylomicron remnants are naturally occurring lipoproteins in the blood that are responsible for the transport of lipids into the liver. Three different mechanisms for this transport are discussed direct uptake by the low-density lipoprotein receptor transport to the low-density lipoprotein receptor-related protein (LRP) mediated by heparan sulfate proteoglycan (HSPG) or direct HSPG-LRP uptake and direct HSPG uptake. One of the prerequisites for particles to be transported by these mechanisms is a mean diameter of less than 100-300 run. 

The table also lists important globulins in blood plasma, with their mass and function. The a- and p-globulins are involved in the transport of lipids (lipoproteins see p. 278), hormones, vitamins, and metal ions. In addition, they provide coagulation factors, protease inhibitors, and the proteins of the complement system (see p. 298). Soluble antibodies (immunoglobulins see p. 300) make up the y-globulin fraction. 

Inhibition of trypsin and other proteases Inhibition of chymotrypsin Transport of lipids... 

Transport of lipids Transport of iron ions Coagulation factor I... 

Lymph may also be of importance as a vehicle for facilitating absorption and transport of lipid-soluble substances but also of particles by specialized cells (M cells) in the gut-associated lymphoid tissue (GALT). 

It has also been observed that sorting and transport of lipids and proteins can be mediated by the formation of small lipid-based domains, so-called rafts. The tenden-... 

Noble, R.C. 1978. Digestion, absorption and transport of lipids in ruminant animals. Prog. Lipid Res., 17, 55-91. 

Scow, R.O., Blanchette-Mackie, E.J., Smith, L.C. 1980. Transport of lipid across capillary endothelium. Fed. Proc. 39, 2610-2617. 

The composition of the milk phospholipids is also an important factor in the structure and transport of lipids in both human and bovine milk. The phospholipids are found predominately in the milk fat globule membrane. 

The newly synthesized triacylglycerol becomes organized into chylomicrons (a type of lipoprotein see next section), which are secreted by the intestinal epithelial cell into the lacteals, small lymph vessels in the villi of the small intestine. Then from the lymphatics, the chylomicrons pass into the thoracic duct, from which they enter the blood and thus contribute to the transport of lipid fuel to various tissues. A feature of chylomicron metabolism is their ability to deliver lipid fuels to extrahepatic tissues. 

The transport of lipids and cholesterol is accomplished by packaging them into lipoprotein complexes this is undertaken by both hepatocytes and enterocytes. Dietary triacylglycerols and cholesterol are packaged by enterocytes into chylomicrons, whereas de novo synthesised triacylglycerols in the liver are packaged in very low-density lipoproteins (VLDLs). 

Pfeffer, P. E., Douds, D. D., Becard, G. Shachar-Hill, Y. (1999). Carbon uptake and the metabolism and transport of lipids in an arbuscular mycorrhiza. Plant Physiology,... 

Lipoproteins are essential for the transport of lipids from the gut and liver to the tissues, and for lipid metabolism. Lipoproteins are spherical particles with a hydrophobic core, covered by a single layer of amphi-pathic molecules phospholipids, cholesterol and one or more apoproteins (of which ten have been isolated these are produced in the liver). The role of these protein coverings is twofold they solubilise hydrophobic lipids and contain cell-targeting signals. 

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