The Fraunhofer Attract group "FAST-PEP" is investigating the rational design of expression vectors and genes. The research focuses on the regulatory elements of transcription and translation (e.g. promoters and UT-regions) as well as the coding sequences. The project aims to rationally optimize these elements in terms of recombinant protein yield that is achieved in different expression systems such as plant and mammalian cells but also in cell-free systems. The optimization takes into account the requirements of process development including the directed modification of the amino acid sequence to aid product purification.