2 - Expression Vectors Employing the trc Promoter

Abstract

This chapter deals with the expression vectors employing trc promoters. As the focus is on trc promoter, the examples given exclusively cover trc expression vectors. The classification of expression vectors, according to transcription promoters, is somewhat arbitrary and has historical reasons originating from a time when a strong promoter was considered the most important asset of an expression vector. However, it was later found that elements important for efficient initiation of translation were equally important. In addition, other sequences around the transcriptional and translational start sites can play an important role in determining the levels of over expression in Escherichia coli. The chapter also discusses various reasons for the popularity of trc promoters. Various vectors are discussed for a detailed analysis. Moreover, a short comparison of trc and tac promoters is described in this chapter. Finally, there is scope for further improvements in expression vectors employing trc promoter. All the existing and anticipated improvements could be integrated into one of the trc expression vectors to offer the researcher a wide variety of vector variants for the most economic and efficient expression of a desired recombinant protein.