Phosphate mediation

Holzman, T. F., and Baldwin, T. O. (1982). Isolation of bacterial luciferases by affinity chromatography on 2,2-diphenylpropylamine-Sepharose phosphate-mediated binding to immobilized substrate analogue. Biochemistry 21 6194-6201. 

Fig. 3. Comparison of transfection efficiencies obtained using PolyFect Reagent, a dendrimer-based transfection reagent, and a calcium phosphate-mediated procedure. COS-7 and HeLa cells were transfected in srx-weU plates with a /3-galactosidase expression plasmid using the appropriate protocol. For the calcium phosphate-mediated transfection, 6 pg of plasmid DNA was used and the medium was changed after 5 h incubation. Transfections were performed in triplicate, and transfection efficiency was measured by monitoring the /3-galactosidase activity of extracts obtained from the transfected cells. The amoimt of /3-galactosidase activity in the extracts correlates with the transfection efficiency. Cells were harvested 48 h post-trans-fection...

Svoboda P, Harms-Ringdahl M (2002) Kinetics of phosphate-mediated oxidation of ferrous ion and formation of 8-oxo-2 -deoxyguanosine in solutions of free 2 -deoxyguanaosine and calf thymus DNA. Biochim Biophys Acta 1571 45-54... 

Some of the enzymes involved in this reaction pathway have been identified. The enzyme of the first step in the reaction pathway, SAM synthetase, is a known enzyme in plant tissues (15). The enzyme converting SAM to ACC has been isolated from tomato tissues (14) and appears to be a pyridoxal phosphate-mediated enzyme. However, the enzyme converting ACC to ethylene has not been isolated as yet, although indications are that it reacts with oxygen by a complex mechanism, perhaps to form free-radical intermediates. 

Ache and coworkers demonstrated that both cyclic nucleotides and inositol phosphates mediate the transduction of environmental chemical signals by the olfactory neurons of P. argus.62 65 Both biochemical and molecular biological techniques have shown that the receptor cells contain various G-protein subunits that would be necessary for signal detection by G-protein-associated chemoreceptors.48 49 66-69 In combination with electrophysiological studies,... 

Mechanistic Studies of the Maillard Reaction with Emphasis on Phosphate-Mediated Catalysis... 

Because of the compensation for the uncatalyzed reaction the phosphate-mediated reaction may be described as ... 

Chen C, Okayama H (1991), Calcium phosphate mediated gene transfer into established cell lines, In Murray EJ (Ed.), Gene Transfer and Expression Protocols, Humana Press, Clifton, pp. 15-21. 

Fig. 4. Proposed production of a glycan-inositol phosphate mediator by insulin. This summarizes Sal-tiel and Cuatrecasas concept for the production of novel mediators through insulin s action. It may, by analogy with the receptor-mediated stimulation of inositol phospholipid metabolism, involve a G-pro-tein. Here it is postulated that the putative Glns may play such a role.

Acid sphingomyelinase is a lysosomal enzyme that catalyzes the breakdown of sphingomyelin to ceramide and phosphoryl-choline.A deficiency of this enzyme leads to lysosomal accumulation of sphingomyelin in patients with Niemann-Pick disease. Recent data indicate that correct intracellular targeting of acid sphingomyelinase to lysosomes is dependent on the mannose 6-phosphate-mediated pathway. Does this imply that the I-cell patient will present with Niemann-Pick symptoms Can I-cell disease be viewed as a constellation of many lysosomal storage diseases ... 

In this chapter, we indicate that the metabolic error (i.e., deficiency of phosphotransferase activity in I-cell disease) gives rise to a secondary phenotype of generalized diminished lysosomal enzyme activity. What other metabolic defects in the mannose 6-phosphate-mediated uptake system could result in such a phenotype, and how would you confirm the defect ... 

OH)2D3 concentrations. Low l,25-(OH)2D3 results in little to no intestinal calcium absorption for soft tissue needs. Thus, blood calcium can be low and secondary hyperparathyroidism develops. The inability to regulate renal handling of phosphate by PTH leads to phosphate-mediated repression of ionized calcium. Serious osteodystrophic lesions occur because of high PTH activity on bone resorption resulting in osteitis fibrosa and osteosclerosis. 

In this particular case, we decided to take advantage of the favorable thermodynamic equilibrium constant that drives the oxidation of phosphite to phosphate mediated by a recently described phosphite dehydrogenase (PTDH) [117] to a nearly irreversible process [118]. The exquisite selectivity of PTDH for phosphite also precludes any side reaction that can occur in case, for example, an ADH is used. These characteristics render PTDH as an ideal candidate for use as a coenzyme regenerating enzyme (GRE) in combination with BVMOs or other NAD(P)H-dependent enzymes. 

Kerbel, R. S., Waghome, C., Man, M. S., Elliott, B. and Breitman, M. L. (1987). Alteration of the tumorigenic and metastatic properties of neoplastic cells is associated with the process of calcium phosphate-mediated DNA transfection. Proc. Natl. Acad. Sci. USA 84, 1263-1267. 

Probably the least well studied of the arARs in terms of phosphorylation, desensitization, or internalization is the a1D-AR. No internalization of those a1D-ARs expressed on the cell surface has been observed (31,32). Yang and coworkers (52) used stably transfected fibroblasts to show that the increase in inositol phosphates mediated by the a1A- and a1B-ARs could be desensitized the increase mediated by the a1D-AR was refractory to agonist-mediated desensitization. In contrast to these results, Garcia-Sainz et al. (53) used stably transfected fibroblasts to show that the a1D-AR could be phosphorylated and desensitized following exposure to norepinephrine. Thus, desensitization of the a1D-AR is very different from that of the other arARs. 

Roberts RZ, Morris AJ (2000) Role of phosphatidic acid phosphatase 2a in uptake of extracellular Upid phosphate mediators. Biochim Biophys Acta 1487 33-49... 

Yu N, Lariosa-Wilhngham KD, Lin FF, Webb M, Rao TS (2004) Characterization of lysophosphatidic acid and sphingosine- l-phosphate-mediated signal transduction in rat cortical ohgodendrocytes. Glia 45 17-27... 

Kabashima T, Kawaguchi T, Wadzinski BE et al (2003) Xylulose 5-phosphate mediates glucose-induced lipogenesis by xylulose 5-phosphate-activated protein phosphatase in rat liver. Proc Natl Acad Sci USA 100 5107-5112... 

In addition to calcium phosphate transfection, methods for DNA transfer into mammalian cells by electroporation [31, 32] and by transfection mediated through cationic lipids, liposome [33-35], biohstics [36] and polymers [37, 38] have been developed. Most of these techniques have been reported to mediate higher transfection efficiencies as compared to calcium phosphate-mediated DNA transfer. Such claims must be regarded with some caution, as all DNA transfer techniques estabhshed so far suffer from high variabihty due to technical difficulties. Other factors to cause major variations in transfection efficiency are the type of cells used and the condition of the cells prior to transfection. 

To test for promoter activity, HeLa cells were transfected with pRSV-B-gal and either p5 2ANOS-L or p5 2BNOS-L, using calcium phosphate-mediated gene transfer (Chen and Okayama, 1987). After 36 hr, cell extracts were prepared and assayed for jS-ga/actosidrtse and luciferase activities. The luciferase activities were normalized to 8-galactosidase activities so that... 

TABLE 11.13 Pyridox phosphate mediated chemical transformations of a-amino acids. After condensation of a-amino acids with pyridoxal-5 -phosphate (PLP) to form pyridoxylidene imino acids (structure shown), chemical transformations may occur in several directions depending on the subsequent bond cleavage step(s)... 

Pyridoxal 5 -Phosphate-Mediated Decarboxylation of an a-Amino Acid 1131 25.4... 

The pyrrolidine moiety in nicotine originates from ornithine, which is first decarboxylated in apyridoxal phosphate-mediated step. After methylation with S-adenosylmethionine (SAME) and ring-closure, cleavage of pyridoxamine phosphate yields the 1-methyl-3,4-dihydropyrrolium salt. 

To generate retroviral particles, murine leukemia virus (MLV) pseudotypes are produced by calcium phosphate-mediated transfection of HEK-293 T cells with a 3 1 ratio of receptor plasmid to pCGP, which encodes the MLV gag andpol genes. When a specific chemokine receptor must be evaluated, HEK-293 T cells transfected transiendy or stably with the receptor should be used. At 4 h posttransfection, fresh medium supplemented with 10 mM -butyric acid is added to increase protein expression supernatant... 

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