The cloning, isolation and characterization of a biologically active human enzyme, urokinase, in E. coli

We have cloned double-stranded cDNA copies of plasminogen activator messenger RNA isolated from human fetal kidney cells. Some of the clones express protein of discrete sizes ranging from 32,000 to 150,000 daltons. These products possess antigenic determinants related to human plasminogen activator from kidney cells, bind to an affinity column specific for serine protease and activate human plasminogen to dissolve fibrin clots.