RESTRICTED INTEGRATION INTO GENOMIC DNA FOLLOWING TRANSFECTION OF CHINESE-HAMSTER OVARY CELLS WITH N-ACETYLGALACTOSAMINE-4-SULFATASE CDNA

The effect of using different conditions of electroporation for introd ucing the gene coding for human N-acetylgalactosamine-4-sulphatase int o Chinese-hamster ovary (CHO) cells has been studied in an effort to i ncrease the yield of recombinant protein, In each case the range of en zyme activities in the medium of transfected cells proved to be simila r, with genetic analysis of a higher producer revealing only one gene copy integrated. Hence, allowing for position effects, the number of g ene copies stably integrated into the CHO genome of all transfectants presumably was low, potentially a single copy in each, This inability to allow high-copy-number integration may suggest a constraint on the levels of this protein which can be tolerated by the cell.