Protein mechanism

Fisher T E, Oberhauser A F, Carrion-Vazquez M, Marszalek P E and Fernandez J M 1999 The study of protein mechanics with the atomic force microscope Trends Biochem. Sci. 24 379-84... 

Sprang, S.R. G protein mechanisms insights from structural analysis. Annu. Rev. Biochem. 66 639-678, 1997. 

FIGURE 5.3 Different types of functional readouts of agonism. Receptors need not mediate cellular response but may demonstrate behaviors such as internalization into the cytoplasm of the cell (mechanism 1). Receptors can also interact with membrane proteins such as G-proteins (mechanism 2) and produce cytosolic messenger molecules (mechanism 3), which can go on to mediate gene expression (mechanism 4). Receptors can also mediate changes in cellular metabolism (mechanism 5). 

Urry, D.W., Entropic elastic processes in protein mechanisms. 1. Elastic structures due to an inverse temperature transition and elasticity due to internal chain dynamics, J. Prot. Chem., 7, 1-34, 1988. 

Anandamide has dual effects on NMDA receptor function. It reduces NMDA Ca2-i- currents, which is mediated by cannabinoid receptors and G-protein mechanisms (Hampson et al. 1998). However, anandamide potentiates NMDA currents due to a direct effect on the NMDA receptor itself. THC did not have the same effect. So anandamide appears to have at least one other CNS effect that is not through the cannabinoid receptors. THC also reduces AMPA/kainate activity, which is mediated by CBl receptors (Shen and Thayer 1999) (table 10.5). THC may in-... 

Steroids have been measured by GC-MS in umbilical cord blood, amniotic fluid, and infancy urine of affected infants, and almost no steroids are found [73]. Only traces of progesterone metabolites were detected. Serum samples from women carrying an LAH fetus have normal concentrations of progesterone metabolites, formed pla-centally, since this organ produces the hormone independently of the StAR protein mechanism. 

Neubig, R. R. (1994). Membrane organization in G-protein mechanisms. FASEB J. 8, 939-946. 

In the following sections, we will discuss the influence of several reaction parameters such as temperature, degree of stirring, and the presence of gas/liquid surfaces on the deactivation behavior of proteins. Mechanisms of enzyme inactivation and aggregation are still poorly understood so, in the best case, the rate of activity loss can be correlated with system parameters such as surface area, power input, or collision frequency. However, the ability to control the resistance of an enzyme to inactivation due to exposure to elevated temperatures is essential for the understanding of thermophilic behavior and for developing rational approaches to enzyme stabilization. 

Since the orexin receptors are Gq protein-coupled (Alexander et al. 2006), one may assume that this also holds true for the presynaptic orexin receptor(s), but so far no data are available. Nonetheless, the six studies carried out in central nervous preparations permit some conclusions on the post-G protein mechanisms. In all instances, the orexins increased the frequency of spontaneous inhibitory or excitatory postsynaptic potentials or currents. The results differed, however, with respect to the influence of tetrodotoxin. In the medial and lateral hypothalamus (van den Pol et al. 1998 Li et al. 2002), dorsal vagal complex (Davis et al. 2003), and caudal nucleus tractus solitarii (Smith et al. 2002), orexins increased the frequency of the miniature potentials or currents also in the presence of tetrodotoxin, suggesting that they directly influenced the vesicle release machinery (references in italics in Table 5). On the other hand, in the prefrontal cortex (Lambe and Aghajanian 2003) and lat-erodorsal tegmentum (Burlet et al. 2002), the orexins did not retain their facilitatory effect in the presence of tetrodotoxin, suggesting an effect further upstream e.g., on Ca2+ and/or K+ channels. 

Roncone R, Barbieri M, Monzani E, Casella L (2006) Reactive nitrogen species generated by heme proteins mechanism of formation and targets. Coord Chem Rev 250 1286-1293... 

The flux of Ca2+ through the ACTH receptor-operated channel leads to the CaM-dependent activation of adenylate cyclase. Hence, either a low concentration of ACTH and/or an increase in K+ concentration leads both to an influx of Ca2+ through this channel and to the activation of adenylate cyclase. Higher concentrations of ACTH acting via a second type of receptor activate adenylate cyclase via the classic Gs protein mechanism. These two ACTH-dependent inputs activate adenylate cyclase in a synergistic fashion. 

Eseapement meehanisms are real possibilities for any protein mechanism that uses oxidant indueed reduetion or reduetant induced oxidation to control the direetion of multiple eleetron transfer at cluster sites. Thus escapements may be active in mitoehondrial Complex 1 (Dutton et al., 1999 Dutton et al., 1998). They should also be eonsidered for anaerobic ribonucleotide reductase (see chapter by M. Sahlin and B-M. Sj berg) and in methionine synthase (see chapter by N. Marsh). 

Siderovski DP, Willard FS. The GAPs, GEFs, and GDIs of het-erotrimeric G-protein alpha subunits. Int. J. Biol. Sci. 2005 1 51-66. Sprang SR. G protein mechanisms insights from structural analysis. Ann. Rev. Biochem. 1997 66 639-678. 

Kidney Renal CL Yes Quantitative distribution of Dose Other drugs Protein Mechanisms of excretion... 

FIGURE 102-5. Nonspecific binding of proteins mechanism. The drug combines with the cell membrane, which in turn causes a nonspecific binding of serum protein. This reaction is seen primarily with the cephalosporins, and no cell lysis or toxicity occurs. Reproduced with permission from Petz LD. Drug-induced haemolytic anaemia. Ballieres Clin Haematol 1980 91 455-482.)... 

Bowman, B.H. (1993) Hepatic Plasma Proteins Mechanisms of Function and Regulation. Academic Press, San Diego, New York. 

Schaffar G et al (2004) Cellular toxicity of polyglutamine expansion proteins mechanism of transcription factor deactivation. Mol Cell 15(1) 95—105... 

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