Apolipoprotein structure

R15. Rosseneu, M., and Labeur, C., Apolipoprotein structure, function and measurement. Curr. Opin. Lipidol. 1, 508-513 (1990). 

Two important hypotheses which describe interactions between proteins and hydrophobic systems are the fluid mosaic model for membrane structure proposed by Singer and Nicholson (60) and the amphipathic apolipoprotein structure proposed by Segreste/ al. (56). In Singer s model for membrane structure shown in Fig. 1, it is proposed that membrane proteins float in a sea of lipid. The nonpolar regions of the protein are in contact with the nonpolar lipids present in the membrane, whereas the polar surface is exposed to the aqueous environment. 

Morales, R., Bema, A., Carpentier, P., Contreras-Martel, C., Renault, F., Nicodeme, M., Chesne-Seck, M.-L. Bernier, F., Schaeffer, C., Diemer, H., Van-Dorsselaer, A., Fontecilla-Camps, J.C., Masson, P., Rochu, D., Chabriere, E. (2006). Serendipitous discovery and X-ray structure of a human phosphate binding apolipoprotein. Structure 14 601-9. Nachon, F., Nicolet, Y., Ticu-Boeck, A., Masson, P., Lockridge, O. 

Mahley RW, Innerarity TL, Rail SC, Jr., Weisgraber KH. Plasma lipoproteins apolipoprotein structure and function. J Lipid Res 1984 25 1277-94. 

Davidson, W.S., Silva, R.A.G.D. 2005. Apolipoprotein structural organization in high-density lipoproteins belts, bundles, hinges and hairpins. Curr. Opin. Lipidol. 16 295-300. 

Morales, R., Berna, A., Carpentier, R, et al., 2006. Serendipitous discovery and X-ray structure of a human phosphate binding apolipoprotein. Structure 14, 601-609. 

Cry.stal structure of truncated human apolipoprotein A-I sngge.sts a lipid-... 

Lipoprotein fraction with apolipoprotein A-I as structural protein. HDL is believed to carry cholesterol away from the blood vessels and back to the liver. High... 

Lipoprotein fraction containing triglycerides and to a lesser degree cholesterol. VLDL is produced by the liver. The main structural protein connected to this lipoprotein class is apolipoprotein B. 

In contrast to MDA and hydroxynonenai, other aldehyde products of lipid peroxidation are hydrophobic and remain closely associated with LDL to accumulate to mil-limolar concentrations. Aldehydes at these elevated levels react with the protein portion of the LDL molecule, apolipoprotein B (apoB). Accumulated aldehydes bind the free amino groups from lysine residues in addition to other functional groups (-OH, -SH) on the apoB polypeptide. Consequently, the protein takes on a net negative charge and complete structural rearrangement results in the formation of ox-LDL. ox-LDL is no longer recognized by the LDL receptor, and has several pro-inflammatory properties (discussed below). 

Each lipoprotein has various proteins called apolipoproteins embedded on the surface (Fig. 9-1). These apolipoproteins serve four main purposes, they (1) are required for assembly and secretion of lipoproteins (such as apolipoproteins B-48 and B-100) (2) serve as major structural components of lipoproteins ... 

FIGURE 9-1. Lipoprotein structure. Lipoproteins are a diverse group of particles with varying size and density. They contain variable amounts of core cholesterol esters and triglycerides, and have varying numbers and types of surface apolipoproteins. The apolipoproteins function to direct the processing and removal of individual lipoprotein particles. (Reprinted from LipoScience, Inc. with permission.)... 

Finally, clinical chemistry of Lp(a) and apolipoprotein (a) is characterized by a variety of problems, caused by the structural complexity and heterogeneity of Lp(a), the homology of apo(a) with plasminogen, and the lack of standardization of analytical methods. 

Fig. 2. Schematic representation of a typical kringle structure, plasminogen, and apolipoprotein (a). [With permission of Scanu et al. (S14).]...

H41. Huby, T., Doucet, C., Dieplinger, H., Chapman, J., and Thillet, J., Structural domains of apolipoprotein(a) and its interaction with apolipoprotein Bl00 in the lipoprotein(a) particle. Biochemistry 33, 3335-3341 (1994). 

Poulain FR, Allen L, Williams MC, et al. Effects of surfactant apolipoproteins on liposome structure implications for tubular myelin formation. Am J Physiol 1992 262(6 Pt 1) L730-L739. 

Fatty liver occurs in kwashiorkor, probably due to lack of protein in the diet, which reduces the synthesis of the structural protein for VLDL (apolipoprotein B). The increased triacylglycerol produced in the liver from fatty acids removed from the blood (i.e. the inter-tissue triac-... 

General Considerations on the Role of Apolipoproteins in Lipoprotein Structure... 

K6. Kostner, G., and Alaupovic, P., Studies of the composition and structure of plasma lipoproteins. C- and N-terminal amino acids of the two nonidentical polypeptides of human plasma apolipoprotein A. FEBS (Fed. Eur. Biochem. Soc.), Lett. 15, 320-324 (1971). 

In the review dealing with the proteins of plasma lipoproteins, Scanu and Ritter have produced a most lucid and detailed discussion of recent advances in this difficult field. An exciting account is given of the isolation of apolipoproteins, their chemical structure, and what is known of their biological functions lipoproteins relevant to patients with dyslipo-proteinemia are also described. 

Apo A-I is the main structural apolipoprotein on HDL particles it is synthesized in hepatic and enteric cells. Bound phosphatidylcholine and sphingomyelin participate in the creation of protein-phospholipid complexes. 

Apo B is structural apolipoprotein for chylomicrons and for VLDL and LDL particles. It is synthesized in enteric and hepatic cells. It is important for cholesterol transport to cells via interaction with LDL receptors. 

Apolipoprotein B. Apo B is a structural apolipoprotein for chylomicrons, VLDL, and LDL particles. It is synthesized in enteric and hepatic cells. It is important for cholesterol transport to cells via interaction with LDL receptors. Nowadays, it seems its clinical relevance in CSF investigation is near Apo A-I and Apo A-II, but in current studies some varieties can be found (A23, T3). 

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