Cell membrane cholesterol

Steck, T.L., Ye, J., Lange, Y. Probing red cell membrane cholesterol movement with cyclodextrin. Biophys. J. 2002, 83, 2118-25. 

Another significant component of many liposome preparations is cholesterol. In natural cell membranes, cholesterol makes up about 10—50% of the total lipid on a molar basis. For liposome preparation, it is typical to include a molar ratio of about 50% cholesterol in the total lipid recipe. The addition of cholesterol to phospholipid bilayers alters the properties of the resultant membrane in important ways. As it dissolves in the membrane, cholesterol orients itself with its polar hydroxyl group pointed toward the aqueous outer environment, approximately even, in a three-dimensional sense, with the glyceryl backbone of the bilayer s phosphodiglyceride components (Fig. 337). Structurally, cholesterol is a rigid component in membrane construction, not having the same freedom of movement that the fatty acid tails of... 

Both suicidal behavior and impulsive aggression have been associated with low levels of brain serotonergic activity [91, 92]. Engelberg suggested that a reduction in serum cholesterol may decrease brain-cell-membrane cholesterol, lower lipid microviscosity, and decrease exposure of protein serotonin receptors on the membrane surface, thus resulting in a poorer uptake of serotonin from the blood and less serotonin entry into brain cells [4]. Other reports have discussed the relationships between cholesterol, serotonin, and depression [6, 93-96]. 

The fluidization and increase in permeability of tumor cell membranes has been reported [43, 44], as well as changes in cellular lipid synthesis during ether phospholipid-induced cytolysis [45]. Direct evidence was found by Diomede et al. [46] and Principe et al. [47] for the importance of the lipid composition of membranes for the sensitivity to antineoplastic ether phospholipids. These authors studied the influence of tumor cell membrane cholesterol content on the sensitivity of leukemic cells [46] and cells derived from three human carcinomas [47] with different rates of cell... 

Cholesterol is a complex lipid that is present in foods that come from animals, such as meat, butter, eggs, and cheese. However, cholesterol is not a fat. Even if you don t eat foods containing cholesterol, your body makes its own supply. Your body needs cholesterol for building cell membranes. Cholesterol is not found in plants, so oils derived from plants are free of cholesterol. However, the body can convert fats in these oils to cholesterol. 

Lange, Y., Ye, J., and Steck, T. L. (2007). Scrambling of phospholipids activates red cell membrane cholesterol. Biochemistry 46,2233-2238. 

Hemolysis data are known to provide a simple and reliable measure for the estimation of CyD-induced membrane damage or cytotoxicity [10, 14). Figure 14.2 shows the hemolysis curves of hydrophilic CyDs on rabbit erythrocytes. The hemolytic effects of methylated CyDs are much higher than those of other CyDs [32, 33). In a series of CyD derivatives, there is a positive correlation between the hemolytic activity and their capacity to solubilize the lipophilic components of the cell membranes (cholesterol and phospholipids). Since the methylated CyDs remove cholesterol significantly from human intestinal epithelial cell monolayers [34], this will... 

Although cholesterol has a bad reputation, it serves many important ftmctions in the body. Like phospholipids and giycolipids, cholesterol is part of cell membranes. Cholesterol also serves as a starting material (or precursor) for the body to synthesize other steroids such as testosterone, a principal male hormone, and estrogen, a principal female hormone. Hormones are chemical messengers that regulate many body processes, such as growth and metabolism. They are secreted by specialized tissues and transported in the blood. 

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