Structures transduction

From a historical point of view ergot alkaloids are closely linked to the classification of adrenoceptors into two major subtypes (a and / ). The discrimination between a- and -adrenoceptors was based on the insensitivity of the latter to ergot alkaloids or -haloalkylamines (Nickerson, 1949). On the basis of structural, transductional, and operational criteria it became apparent that the existence of two subtypes of a-adrenoceptors, the ai-adrenoceptor, sensitive to blockade by prazosin, and the a2-adrenoceptor, sensitive to blockade by yohimbine or rauwolscine, makes it more appropriate to classify adrenoceptors into three major subtypes the aj-adrenoceptors, az-adrenoceptors, and -adrenoceptors (Bylund, 1988). 

Schindeiin N, Kisker C, Sehiessman J L, Howard J B and Rees D C 1997 Structure of ADP center dot AiF(4)(-)-stabiiized nitrogenase compiex and its impiications for signai transduction Nature 387 370-6... 

In this chapter we describe some examples of structures of membrane-bound proteins known to high resolution, and outline how the elucidation of these structures has contributed to understanding the specific function of these proteins, as well as some general principles for the construction of membrane-bound proteins. In Chapter 13 we describe some examples of the domain organization of receptor families and their associated proteins involved in signal transduction through the membrane. 

A tremendous effort has been made by scientists to understand and to mimic the most fascinating and inaccessible of the organs developed by evolution. In spite of the efforts devoted to observing and understanding the morphology of the different components of the nervous system, the conformational structure of the amorphous channels responsible for signal transduction remains unsolved. Nevertheless, the main problem related to the nervous system is centered on the nervous impulse how it is formed, how many components it has, what kind of information drives every component, and how we can interact with these components in order to... 

The contractile apparatus may be thought of as the sum of those intracellular components which constitute the machinery of chemomechanical transduction. It is the set of proteins which convert the chemical energy of the terminal phosphate ester bond of ATP into mechanical work. The structure of the contractile apparatus is determined by the connections between the various protein molecules via specific binding sites or, in a minority of cases, via labile covalent linkages. The kinetics of the contractile machinery are determined by the regulation of changes in these connections. 

Rousseau F, Schymkowitz J. A systems biology perspective on protein structural dynamics and signal transduction. Curr Opin Struct Biol 2005 15 23-30. 

While the fluid mosaic model of membrane stmcture has stood up well to detailed scrutiny, additional features of membrane structure and function are constantly emerging. Two structures of particular current interest, located in surface membranes, are tipid rafts and caveolae. The former are dynamic areas of the exo-plasmic leaflet of the lipid bilayer enriched in cholesterol and sphingolipids they are involved in signal transduction and possibly other processes. Caveolae may derive from lipid rafts. Many if not all of them contain the protein caveolin-1, which may be involved in their formation from rafts. Caveolae are observable by electron microscopy as flask-shaped indentations of the cell membrane. Proteins detected in caveolae include various components of the signal-transduction system (eg, the insutin receptor and some G proteins), the folate receptor, and endothetial nitric oxide synthase (eNOS). Caveolae and lipid rafts are active areas of research, and ideas concerning them and their possible roles in various diseases are rapidly evolving. 

Section V deals with aspects of extracellular and intracellular communication. Topics covered include membrane structure and function, the molecular bases of the actions of hormones, and the key field of signal transduction. 

B. Perman, V. Srajer, Z. Ren, T. Teng, C. Pradervand, T. Ursby, D. Bourgeois, F. Schotte, M. Wulff, R. Kort, K. HeUingwerf, and K. Moffat, Energy transduction on the nanosecond time scale early structural events in a xanthopsin photocycle. Science 279, 1946-1950 (1998). 

Phytosterols have been demonstrated as being anti-cancer components in the diet (Awad and Fink 2000). Scientific studies indicate that phytosterols may offer profection against colon, breast and prostate cancers (Vanderhaeghe and Bouic, 2000). The possible mechanisms, as reported by these authors, include the effect of phytosterols on membrane structure and function and on the signal transduction pathways that regulate tumor growth and apoptosis. The rice bran derived phytosterol-cycloartenol-ferulic acid ester on the central nervous system has been studied by Hiraga et al. (1993). 

C6t6, F. and Hahn, M.G. (1994) OUgosaccharins structures and signal transduction. Plant MolBiol. 26 1375-1411. 

The structure of PGIP is similar to that of proteins involved in signal transduction... 

Transduction of the energy from ATP to movement of the cations may involve long-range structural transitions in the protein since ATP binding and phosphorylation takes place in the large cytoplasmic protrusion of the a subunit, while cation sites may be located in intramembrane domains. It is therefore important to establish relationships between the structural changes in the a subunit and ion binding or occlusion to see if the different exposure of bonds to proteolysis reflect the orientation and specificity of the cation sites. 

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