Translation, recombinant genes

The human gene will be replicated, along with the vector in the recombinant DNA, but it won t necessarily be expressed. This only occurs if its disposition within the recombinant molecule is such that it is transcribed as mRNA and then translated into protein. For transcription, the gene must be positioned appropriately with respect to a bacterial promoter. For successful translation, the gene must be free of introns (Chap. 17), and its transcript must contain a bacterial ribosomal binding site (Chap. 17) at the correct location. 

Cell-free translation system, used for the identification of cloned genes and gene expression, has been investigated extensively as a preparative production system of commercially interesting proteins after the development of continuous-flow cell-free translation system. Many efforts have been devoted to improve the productivity of cell-free system [1], but the relatively low productivity of cell-free translation system still limits its potential as an alternative to the protein production using recombinant cells. One approach to enhance the translational efficiency is to use a condensed cell-free translation extract. However, simple addition of a condensed extract to a continuous-flow cell-free system equipped with an ultrafiltration membrane can cause fouling. Therefore, it needs to be developed a selective condensation of cell-free extract for the improvement of translational efficiency without fouling problem. 

The desired gene/cDNA is normally amplified, sequenced and then introduced into an expression vector that facilitates its introduction and expression (transcription and translation) in an appropriate producer cell type. All recombinant therapeutic proteins approved to date are produced in E. coli, S. cerevisiae or in animal cell lines (mainly CHO or BHK cells). The general... 

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