Transformation-associated recombination

Transformation-associated recombination frani -activation response region Trani-activator of transcription... 

Kouprina,N., and Larionov, V. (2008) Selective isolation of genomic loci from complex genomes by transformation-associated recombination cloning in the yeast Saccharomyces cerevisiae, Nat Protoc. 3, 371-377. 

Kouprina N, Annab L, Graves J et al (1998) Functional copies of a human gene can be direcdy isolated by transformation-associated recombination cloning with a small 3 end target sequence. Proc Natl Acad Sci USA 95 4469 474... 

Leem SH, Noskov VN, Park JE et al (2003) Optimum conditions for selective isolation of genes from complex genomes by transformation-associated recombination cloning. Nucleic Acids Res 31 e29... 

On the other hand, if the products separate rapidly or react with other species (or catalysts) that generate the final product at a rate that is competitive with that of reversion to reactants, the overall rate of product formation will increase. Thus, the reaction of the product of the first step with a third entity can be the key to enhancing the rate, along with the conventionally expected stabilization of the transition state. In the extreme, if the reaction is made irreversible by a process that prevents the products from recombining, the net rate of product formation is greatly facilitated, allowing the full effect of catalysis to be observed in the net rate of transformation. The availability of routes that promote the forward reaction requires catalytic species be present in the vicinity of the initially formed complex because diffusion is expected to be slower than the separation of the immediate products. While such a situation is unusual with small catalysts, it is likely to be common with large catalysts, such as enzymes, where a catalytic array is present once the substrate has become associated (Scheme 1). 

The climate for permission by regulatory agencies, particularly by the FDA in the United States to use immortalized CHO cells for the production of recombinant proteins was not favorable in the early 1980s. Discussions about risks associated with the use of mammalian cells were controversial and had been initiated more than two decades earlier [134] when a first generation of classical biological products (i.e., vaccines and the natural interferons) were developed on the basis of primary monkey kidney cells, human diploid cells and, later, transformed mammalian cells. 

Similarly, PrP extracted from hamster brains into 10 mM aqueous sodium phosphate solution at pH 7.5 yielded CD and infrared spectra that are typical for a-helical proteins (Pan et ai, 1993). Overall, the optical spectra thus indicate that natural PrP, with its numerous post-translational modifications has a similar conformation as recombinant PrP expressed in E. coli and dissolved in nondenaturing aqueous solvents. On a different line, evidence has also been presented that neither the C-terminal GPI-anchor nor the carbohydrate moieties in the positions 181 and 197 (Fig. 1) are essential molecular components with regard to the transformation of PrP into forms that are associated with prion infectivity (Stahl et al, 1987). These data clearly emphasize the relevancy of structural studies with recombinant prion proteins for deeper insights into structure and function of natural prion proteins. 

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