Expression of human plasminogen in Drosophila Schneider S2 cells

The cDNA that encodes full-length human plasminogen (Glu(1)-hPg) has been e xpressed in Drosophila Schneider S2 cells under the influence of the Drosop hila BiP protein signal sequence, which allowed the protein to be secreted into the medium. A procedure was devised for clonal selection of high-expre ssing cells, which were then used for large-scale expression of 10-15 mg/li ter of the protein in the culture medium. The protein produced using this s ystem was extensively characterized and contained full-length recombinant ( r) Glu(1)-hPg plasminogen. As with human plasma Glul-hPg, the SE-expressed protein underwent the Cl--induced transition to the tight conformation, whi ch resulted in a weakly activatable zymogen. The addition of the ligand, E- amino caproic acid, induced the relaxed conformation of r-Glu(1)-hPg, which was highly activatable, again in agreement with similar data for human pla sma Glu(1)-hPg. The thermal stability of the S2-expressed r-Glu(1)-hPg also correlated well with that of human plasma hPg, These studies show that int act r-Glu(1)-hPg can be produced in high yield in Drosophila Schneider S2 c ells, which possesses similar properties to its human plasma counterpart. ( C) 1999 Academic Press.