Cloning, nucleotide sequencing and expression of cDNAs encoding mouse urokinase‐type plasminogen activator

Controlled extracellular proteolysis is catalyzed in part by the secretion of plasminogen activators. As a step in the study of the expression of these enzymes in mouse tissues, we have isolated five cDNAs encoding the mouse urokinase‐type plasminogen activator from a cDNA library prepared with size‐selected mRNA from MSV‐transformed 3T3 cells. The longest cDNA insert contains the entire coding region of mouse urokinase, 58 base pairs of the 5′ non‐coding region, and the entire 3′ non‐coding region, which is 942 base pairs long. The deduced protein sequence, which starts with a signal peptide of 20 amino acids, shows extensive homology to that of human and porcine urokinase. However, in contrast to these enzymes, mouse urokinase contains no N‐glycosylation site. Bacteria harbouring one of the recombinant plasmids synthesize and secrete into their periplasm a protease indistinguishable from mouse urokinase.