Abstract: The invention relates to a kit to be used for the identification of a secretion cassette, which in eukaryotic cells gives rise to a higher level of synthesis/secretion of a protein of interest, the coding sequence of which being flanked by the first and the second set of genetic elements, respectively, compared to the other secretion cassettes present in the kit containing the coding sequence at the corresponding position, as well as to a method wherein the kit is used and the use of the kit, whereby the best secretion cassette will be obtained.

Abstract: The invention relates to a method to generate rational libraries comprising genetic elements which are involved in transcriptional and/or translational regulation of a gene and devised to increase the production yield of the encoded protein as well as to the rational library and to the application of said rational library.

Abstract: The invention relates to a kit to be used for the identification of a secretion cassette, which in eukaryotic cells gives rise to a higher level of synthesis/secretion of a protein of interest, the coding sequence of which being flanked by the first and the second set of genetic elements, respectively, compared to the other secretion cassettes present in the kit containing the coding sequence at the corresponding position, as well as to a method wherein the kit is used and the use of said kit, whereby the best secretion cassette will be obtained.

Abstract: The invention relates to a method of producing genetically modified eukaryotic cells with optimised growth characteristics wherein a recombinant first nucleotide sequence has been integrated into a desired position in the genome. The sequence contains at least one gene encoding a plasma membrane protein with either toxin-receptor or toxic properties and allowing for surface expression based cell sorting to identify a suitable genomic integration locus. The invention also relates to a second exogenous nucleotide sequence containing at least one protein of interest as well as a vector, which aids in the site specific exchange of the first with the second nucleotide sequence. Efficient exchange is achieved by a stringent selection strategy that will kill all cells still expressing the plasma membrane protein.

Abstract: Mammalian signal peptides can be used to aid in the secretion of mammalian proteins that are normally not secreted. By inactivating signals normally present in the 3? UTRs of mRNAs encoding proteins that are normally not secreted from mammalian cells, the proportion of such mRNA molecules directed to free and cytoskeletal bound polysomes can be reduced.