Dual vector systems, and mammalian host cells comprising them, for the expression of multi chain molecules are provided where each vector employs a different promoter driving the expression of a selectable marker. The mammalian host cells can be used for producing a recombinant protein of interest in a mammalian cell culture.

The present invention relates to a vector comprising a polynucleotide encoding a modified glutamine synthetase (GS), and a method for preparing a target protein employing the same. More particulary, the present invention relates to a modified GS having an increased sensitivity to a glutamine synthetase (GS) inhibitor, a polynucleotide encoding the modified GS, a vector comprising the polynucleotide, a transformat comprising the vector, and a method for preparing a target protein using the transformat.

Provided are novel selectable markers and uses thereof. Specifically, provided are uses of nucleotide sequences encoding a glutamine synthetase (GS) derived from Alligator, green anole, or spotted gar as selectable markers for identifying genomic loci with high transcriptional activity or host cells having high productivity of a protein of interest, and/or for accelerating the identification process. Related methods of screening, methods of production, and expression systems are also included.

Disclosed are a novel expression vector for efficient expression of recombinant proteins in mammalian cells, a mammalian cell transformed with the vector, and a method for production of the mammalian cell. The expression vector is an expression vector for expression of a mammalian protein and includes a gene expression regulatory site, and a gene encoding the protein downstream thereof, and an internal ribosome entry site further downstream thereof, and a gene encoding a glutamine synthetase further downstream thereof, and a dihydrofolate reductase gene downstream of either the same gene expression regulatory site or another gene expression regulatory site in addition to the former.

The present disclosure generally relates to technologies for the degradation a systemic toxin in vivo by enhancing the metabolic functionality of the lungs. Such technologies comprise introducing, to pulmonary tissue of a subject, a composition comprising at least one enzyme known to enzymatically break down at least one toxin present systemically in the subject. The provided technologies enable the lung to behave as a tunable metabolic organ, facilitating the removal of toxins from the systemic circulation of a subject, such as a subject having a condition resulting in the toxic accumulation or an endogenous metabolite, and a subject who has consumed a toxic substance.

Disclosed herein are novel selectable markers and uses thereof. Specifically, provided herein are uses of nucleotide sequences encoding a glutamine synthetase (GS) derived from platypus, turtle, rat, opossum, wombat, or zebra finch as selectable markers for identifying genomic loci with high transcriptional activity or host cells having high productivity of a protein of interest, and/or allowing accelerated cell isolation expressing a protein of interest. Related methods of screening, methods of production, and expression systems are also included.

The invention relates to transgenic plants exhibiting dramatically enhanced growth rates, greater seed and fruit/pod yields, earlier and more productive flowering, more efficient nitrogen utilization, increased tolerance to high salt conditions, and increased biomass yields. In one embodiment, transgenic plants engineered to over-express both glutamine phenylpyruvate transaminase (GPT) and glutamine synthetase (GS) are provided. The GPT+GS double-transgenic plants of the invention consistently exhibit enhanced growth characteristics, with T0 generation lines showing an increase in biomass over wild type counterparts of between 50% and 300%. Generations that result from sexual crosses and/or selfing typically perform even better, with some of the double-transgenic plants achieving an astounding four-fold biomass increase over wild type plants.

The present invention relates to a novel GS (glutamine synthetase) gene knock out transgenic HEK293 (human embryonic kidney 293) cell line and a production method of a target protein using the said transgenic HEK293 cell line. Particularly, the present inventors eliminated the expression of GS in the HEK293 cells in order to overcome a barrier of the cell line selection caused by the over-expression of GS, for producing a target protein by GS/MSX system, by which the efficiency of the cell line selection for the high production of a target protein would be increased and accordingly the protein production by the selected cell line would be increased, suggesting that the human originated transgenic HEK293 cell line could be efficiently used for the production of a target protein.

The present invention relates to a vector comprising a polynucleotide encoding a modified glutamine synthetase (GS), and a method for preparing a target protein employing the same. More particularly, the present invention relates to a modified GS having an increased sensitivity to a glutamine synthetase (GS) inhibitor, a polynucleotide encoding the modified GS, a vector comprising the polynucleotide, a transformant comprising the vector, and a method for preparing a target protein using the transformant.

Disclosed is an expression vector comprising a polynucleotide encoding for a glutamine synthetase with reduced activity compared to a wild type glutamine synthetase. Also disclosed are host cells, methods for preparing stable cell line, methods of producing polypeptide of interest, and kits thereof.