Adenosine triphosphate family

P-Glycoprotein (P-gp), a member of the adenosine triphosphate (ATP)-binding cassette family of membrane transporters, is encoded by the human multidrug-resistance (MDRl, ABCBl) gene (15). This integral membrane protein serves as an... 

Phosphorylation and dephosphorylation Phosphorylation reactions are catalyzed by a family of enzymes called protein kinases that use adenosine triphosphate (ATP) as a phosphate donor. Phosphate groups are cleaved from phosphorylated enzymes by the action of phosphoprotein phosphatases (Figure 5.18). 

Fig. 9.1 Schematic diagram illustrating A3 adenosine receptor localization in the brain. ADO adenosine ADA adenosine deaminase ATP adenosine triphosphate, AMP adenosine mono-phospate AKA adenosine kinase T bidirezional nucleoside transporter NPTDase family of ecto-nucleotidases, including NPTDase 1,2,3. During cerebral ischemia, extracellular ADO concentration increases acting on A3 adenosine receptors located on different cell type...

Proteins of a certain family usually exhibit structurally similar binding sites a prominent example is the adenosine triphosphate (ATP)-binding site of the... 

Several classes of serine/threonine kinases are known and these enzymes consist of a catalytic domain which transfers phosphate groups from adenosine triphosphate (ATP) to the targets, and a regulatory domain which modulates the activity of the catalytic domain through interaction with second messengers such as cyclic nucleotides, calcium ion, and DAGs. The family of kinases, their activators, and typical synthetic inhibitors are shown in Table 4.5. 

The application of LSR to amino-acids has received some attention. (451-456, 498) Such studies are an essential preliminary to the use of LSR for amino-acid sequence determination in simple peptides and proteins. The latter are discussed more comprehensively in Section G. A detailed study has been made (453) of the interaction of Eu(iii), Pr(iii), Gd(iii), and La(iii) with iV-acetyl-L-3-nitrotyrosine in order to characterize the nitrotyrosine residue as a potential specific lanthanide binding site in proteins. The parameters of the dipolar interaction indicate a significant contribution from non axially symmetric terms. The conformations of the nucleotides cyclic j8-adenosine 3, 5 -phosphate (3, 5 -AMP) (457, 458) and adenosine triphosphate (ATP) (459) have been deduced using LSR. In the former case the conformation of the ribose and phosphate groups is consistent with the solid state structure. A combination of lanthanide shift and relaxation reagents was used to deduce the most favoured family of conformations for ATP in aqueous solution. One of these conformations corresponds closely to one of the crystal structure forms. 

Carrier-mediated transport of drugs and their metabolites has recently been recognized as an important issue in pharmaceutical research. There is a wealth of information that suggests that transporters are responsible both for the uptake and efflux of drugs and other xenobiotics, and may be key determinants of the disposition of a drug [91,92]. Transporter proteins are divided into two categories (1) the adenosine triphosphate (ATP) binding cassette (ABC) transporter superfamily and (2) the solute carrier (SLC) family of proteins. 

Kinases are enzymes that transfer a phosphate group from adenosine triphosphate (ATP), or other trinucleotide, to a number of biological substrates, such as sugars or proteins. They are part of a larger family of enzymes known as group transferases, but are limited to phosphate transfers. A typical reaction catalyzed by a kinase (e.g., hexokinase) is the phosphorylation of glucose upon its entry into a cell... 

Fig. 76.2 Polyphenols and polyphenol-rich sources induce endothelial-dependent NO- and EDH-mediated relaxations. Polyphenols are potent inducers of the oidothelial formation of nitric oxide (NO) and endothelium-derived hyperpolarizatitm (EDH) via a redox-soisitive mechanism. SKca small conductance calcium-activated potassium channels, IKca intermediate conductance calcium-activated potassium channels, Src Src family kinase, PI3K phosphatidylinositol 3-kinase, eNOS endothelial NO synthase, L-Arg L-arginine, sGC soluble guanylyl cyclase, GTP guanosine triphosphate, cGMP cyclic guanosine monophosphate, AA arachidonic acid, COX cyclooxygenase, ATP adenosine triphosphate, cAMP cyclic adenosine monophosphate...

An ex vivo study with rat hepatocytes found a strong correlation between the cytotoxicity of a flavonoid and its ability to induce an early collapse of the mitochondrial transmembrane potential [6]. In contrast, nontoxic flavonoids had no effect on the transmembrane potential. As discussed previously, the ability of flavonoids and isoflavones to inhibit mitochondrial respiration and adenosine triphosphate (ATP) synthesis or uncouple oxidative phosphorylation represents a potential mechanism whereby they can trigger dissipation of the transmembrane potential and thus cytochrome c-dependent apoptosis. Thus, it is interesting to note that epicatechin, which had little or no proapoptotic effect in cancer cells [64] and exerted antiapoptotic effects in primary culture models [7,8,59], had essentially no inhibitory effect against complex I, II, or HI activity and FoFi-ATPase activity [24,25]. However, the preceding discussion has also indicated that the pro- or antiapoptotic effects of flavonoids may be explained by more specific mechanisms, potentially independently of their antioxidant capacity. These include effects on protein kinase cascades and gene expression, including MARK and the Bcl-2 family of proteins. 

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