Receptor action membranes

Heidmann, T. Oswald, R.E. and Changeux, J.-P. Multiple sites of action for noncompetitive blockers on acetylcholine receptor rich membrane fragments from Torpedo marmorata. Biochemistry 22 3112-3127, 1983. 

It is not clear whether V(V) or V(IV) (or both) is the active insulin-mimetic redox state of vanadium. In the body, endogenous reducing agents such as glutathione and ascorbic acid may inhibit the oxidation of V(IV). The mechanism of action of insulin mimetics is unclear. Insulin receptors are membrane-spanning tyrosine-specific protein kinases activated by insulin on the extracellular side to catalyze intracellular protein tyrosine phosphorylation. Vanadates can act as phosphate analogs, and there is evidence for potent inhibition of phosphotyrosine phosphatases (526). Peroxovanadate complexes, for example, can induce autophosphorylation at tyrosine residues and inhibit the insulin-receptor-associated phosphotyrosine phosphatase, and these in turn activate insulin-receptor kinase. 

Alkaloids have their own signalling system. Receptors and membranes play an active role in this system. The role of biological membranes in alkaloid signalling is also connected with the action of the specific ion channels of... 

Langmuir-Blodgett Technology and Receptor Action in Stabilized Lipid Membranes... 

Receptor Action In Analytical Membranes. This work has Identified the Importance of some of the relevant parameters associated with organized lipid matrix ion conduction. Receptors embedded In these matrices should function to perturb one or more of the three compartmenta 1 zones of the BLM. A number of features significant to electrochemical receptor operation follow ... 

Figure 17-4 Proposed biochemical mechanisms of cholniEr-gic receptor action. A. ACh activates a G protein (a. fi. yir the phospholipase system to activate the membrane entyiix phospholipase C (PL(f), enhancing muscle contraction B. Inhh lion of adenylate cyclase system through an inhibitory G piote (ai) to cause muscle relaxation.

Vizi ES. 2000. Role of high-affinity receptors and membrane transporters in nonsy-naptic communication and drug action in the central nervous system. Pharmacol. Rev. 52 63-89... 

Norman, A.W., Mizwicki, M.T. and Norman, D.P. (2004) Steroid-hormone rapid actions, membrane receptors and a conformational ensemble model. Nature Reviews Drug Discovery, 3,... 

Figure 21.32 shows the architecture of an LDL particle. The interior consists of many molecules of cholesteryl esters (the hydroxyl group of the cholesterol is esterified to an unsaturated fatty acid, such as linoleate). On the surface, protein (apoprotein B-lOO), phospholipids, and unesterified cholesterol are in contact with the aqueous medium of the plasma. The protein portions of LDL particles bind to receptor sites on the surface of a typical cell. Refer to the discussion of membrane receptors in Section 8.6 for a description of the process by which LDL particles are taken into the cell as one aspect of receptor action. This process is typical of the mechanism of uptake of lipids by cells, and we shall use the processing of LDL as a case study. LDL is the major player in the development of atherosclerosis. 

Many examples of essential oil effects abound in animal studies, for example, the sedative action of lavender on the overall activity of mice decreased when exposed to lavender vapor (f. angustifolia P. Miller) its components linalool and linalyl acetate showed a similar effect (Buchbauer et al., 1992). A possible explanation for the observed sedative effects was shown by linalool, which produced a dose-dependent inhibition of the binding of glutamate (an excitatory neuretransmitter in the brain) to its receptors on membranes of the rat cerebral cortex (Elisabetsky et al., 1995). More recently, this action was related to an anticonvulsant activity of linalool in rats (Elisabetsky et al., 1999). Other oils with sedative activity were found to be neroli and sandalwood active compo nents included citronellal, phenylethyl acetate, linalool, linalyl acetate, benzaldehyde, terpineol, and isoeugenol (in order of decreasing activity). 

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