Phospholipids activity

Delerive, P., Furman, C., Teissier, E., Fruchart, J., Duriez, P., and Staels, B. (2000). Oxidized phospholipids activate PPARalpha in a phospholipase A2-dependent manner. FEBS Lett. 471,... 

Catala, A. (2009). Lipid peroxidation of membrane phospholipids generates hydroxy-aUcenals and oxidized phospholipids active in physiological and/or pathological conditions. Chemistry and Physics of Lipids, 157, 1—11. 

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

Elliott, D. and J. Skinner Calcium-dependent, phospholipid-activated protein kinase in plants Phytochemistry 4610. 

Fig. 45.5. A. Structures of vitamin K derivatives. Phylloquinone is found in green leaves, and intestinal bacteria synthesize menaquinone. Humans will convert menadione to a vitamin K active form. B. Vitamin K-dependent formation of y-carboxyglutamate residues. Thrombin, Factor VII, Factor IX, and Factor X are bound to their phospholipid activation sites on cell membranes by Ca ". The vitamin K-dependent carboxylase, which adds the extra carboxyl group, uses a reduced form of vitamin K (KH2) as the electron donor and converts vitamin K to an epxjx-ide. Vitamin K epoxide is reduced, in two steps, back to its active form by the enzymes vitamin K epoxide reductase and vitamin K reductase.

The third phase of extrinsic thromboplastin formation seems to be somewhat less complex than the first two steps. This phase involves the interaction of product I and platelet phospholipids. How the phospholipids are released from platelets during the formation of intrinsic thromboplastin is still debated, but two facts are significant normal platelets have no phospholipid activity, and the development of phospholipid activity is associated with viscous metamorphosis and granular release from platelets. Either product I or PTA has been thought to produce viscous metamorphosis (see below). In the formation of product II, product I is thought to act as an enzyme on the platelet phospholipid to yield product II. 

Memon AR, Chen Q, Boss WF. Inositol phospholipids activate plasma membrane ATPase in plants. Biochem Biophys Res Commun 1989 162 1295-1301. 

There has been extensive activity in the study of lipid monolayers as discussed above in Section IV-4E. Coexisting fluid phases have been observed via fluorescence microscopy of mixtures of phospholipid and cholesterol where a critical point occurs near 30 mol% cholesterol [257]. 

There has been a surge of research activity in the physical chemistry of membranes, bilayers, and vesicles. In addition to the fundamental interest in cell membranes and phospholipid bilayers, there is tremendous motivation for the design of supported membrane biosensors for medical and pharmaceutical applications (see the recent review by Sackmann [64]). This subject, in particular its biochemical aspects, is too vast for full development here we will only briefly discuss some of the more physical aspects of these systems. The reader is referred to the general references and some additional reviews [65-69]. 

Brent et al., 1989] Brent, G. A., Dunn, M. K., Harney, J. W., Gulick, T., and Larsen, P. R. Thyroid hormone aporeceptor represses Ta inducible promoters and blocks activity of the retinoic acid receptor. New Biol. 1 (1989) 329-336 [Cevc and Marsh, 1987] Cevc, G., and Marsh, D. Phospholipid Bilayers Physical Principles and Models. John Wiley Sons, New York, 1987. 

Phospholipids. Phospholipids, components of every cell membrane, are active determinants of membrane permeabiUty. They are sources of energy, components of certain enzyme systems, and involved in Hpid transport in plasma. Because of their polar nature, phosphoUpids can act as emulsifying agents (42). The stmcture of most phosphoUpids resembles that of triglycerides except that one fatty acid radical has been replaced by a radical derived from phosphoric acid and a nitrogen base, eg, choline or serine. 

QUANTUM-CHEMICAL MODELLING OL PROCESSES OF INTERACTION OF ACTIVE FORMS OF OXYGEN WITH PHOSPHOLIPIDES... 

The aims of the given work ar e investigation of interaction processes of active forius of oxygen with phospholipids under action of natural antioxidant QIO development of chemical model on the basis of physical and chemical behaviour of QIO and corresponding mathematical model. 

Proteins that can flip phospholipids from one side of a bilayer to the other have also been identified in several tissues (Figure 9.11). Called flippases, these proteins reduce the half-time for phospholipid movement across a membrane from 10 days or more to a few minutes or less. Some of these systems may operate passively, with no required input of energy, but passive transport alone cannot establish or maintain asymmetric transverse lipid distributions. However, rapid phospholipid movement from one monolayer to the other occurs in an ATP-dependent manner in erythrocytes. Energy-dependent lipid flippase activity may be responsible for the creation and maintenance of transverse lipid asymmetries. 

Eicosanoids, so named because they are all derived from 20-carbon fatty acids, are ubiquitous breakdown products of phospholipids. In response to appropriate stimuli, cells activate the breakdown of selected phospholipids (Figure 25.27). Phospholipase Ag (Chapter 8) selectively cleaves fatty acids from the C-2 position of phospholipids. Often these are unsaturated fatty acids, among which is arachidonic acid. Arachidonic acid may also be released from phospholipids by the combined actions of phospholipase C (which yields diacyl-glycerols) and diacylglycerol lipase (which releases fatty acids). 

Dukhovich, A. F., et al. (1988). Choline-containing phospholipids as specific activators and stabilizers of firefly luciferase. Dokl. Akad. Nauk SSSR 298 1257-1260. 

Activated partial thromboplastin time (aPTT) is a coagulation assay, which measures the time for plasma to clot upon activation by a particulate substance (e.g., kaolin) in the presence of negatively charged phospholipids. 

Adaptor Proteins. Figure 1 Adaptor protein domains. A scheme of the domain structures of some well-characterized adaptor proteins is shown. Descriptions of domain characteristics are in main text except C2, binds to phospholipids GTPase activating protein (GAP) domain, inactivates small GTPases such as Ras Hect domain, enzymatic domain of ubiquitin ligases and GUK domain, guanylate kinase domain. For clarity, not all domains contained within these proteins are shown. 

Akt is activated by binding of plasma membrane phospholipids downstream of insulin receptors, growth and survival factor receptors in a phosphoinositide 3-kinases dependent manner. In humans, there are three genes in the Akt family Aktl, Akt2 and Akt3. Their respective fimctions are still under investigation. 

Tyrosine phosphorylated IRS interacts with and activates PI 3-kinase [3]. Binding takes place via the SRC homology 2 (SH2) domain of the PI 3-kinase regulatory subunit. The resulting complex consisting of INSR, IRS, and PI 3-kinase facilitates interaction of the activated PI 3-kinase catalytic subunit with the phospholipid substrates in the plasma membrane. Generation of PI 3-phosphates in the plasma membrane reemits phospholipid dependent kinases (PDKl and PDK2) which subsequently phosphorylate and activate the serine/threonine kinase Akt (synonym protein... 

PLTP is responsible for the majority of phospholipid transfer activity in human plasma. Specifically, it transfers surface phospholipids from VLDL to HDL upon lipolysis of triglycerides present in VLDL. The exact mechanism by which PLTP exerts its activity is yet unknown. The best indications for an important role in lipid metabolism have been gained from knockout experiments in mice, which show severe reduction of plasma levels of HDL-C and apoA-I. This is most likely the result of increased catabolism of HDL particles that are small in size as a result of phospholipid depletion. In addition to the maintenance of normal plasma HDL-C and apoA-I concentration, PLTP is also involved in a process called HDL conversion. Shortly summarized, this cascade of processes leads to fusion of HDL... 

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