DHFR coamplification of t-PA in DHFR+ bovine endothelial cells: in vitro characterization of the purified serine protease.

Autor: Connors RW; Department of Molecular Genetics, Smith Kline and French Laboratories, King of Prussia, PA 19406-0939., Sweet RW, Noveral JP, Pfarr DS, Trill JJ, Shebuski RJ, Berkowitz BA, Williams D, Franklin S, Reff ME
Jazyk: angličtina
Zdroj: DNA (Mary Ann Liebert, Inc.) [DNA] 1988 Nov; Vol. 7 (9), pp. 651-61.
DOI: 10.1089/dna.1988.7.651
Abstrakt: High-level expression of human tissue-type plasminogen activator was accomplished in endothelial cells by a novel approach to dihydrofolate reductase (DHFR) coamplification in DHFR+ cells. A tripartite mammalian expression vector coding for DHFR, neomycin phosphotransferase, and the t-PA gene was introduced into bovine endothelial cells by transfection and selection for G418 resistance. Upon methotrexate selection of these transformants, we obtained endothelial cells that had amplified the plasmid-encoded DHFR and t-PA genes. As a result, cell lines were isolated that efficiently produced t-PA (greater than 4 pg/cell.day). This t-PA was purified and compared with recombinant t-PA produced in Chinese hamster ovary cells. These two t-PA samples differed in carbohydrate composition, and amounts of 530 and 527 amino acid forms but had similar in vitro activity.
Databáze: MEDLINE