Expression in E. coli of finger-domain lacking tissue-type plasminogen activator with high fibrin affinity.

Tissue-type plasminogen activator (t-PA) has a high affinity for fibrin and induces lysis of fibrin (fibrinolysis) on the surface of fibrin without degrading circulating fibrinogen. cDNA for t-PA which lacks the 'finger-domain' (the site for fibrin affinity) was isolated from Detroit 562 cells. Analysis of the nucleotide sequence revealed a lack of the sequences which code for the finger-domain. A plasmid (pDPAT 1) containing the Escherichia coli tac promoter/operator and the cDNA sequence coding for 'finger-domain lacking t-PA' was constructed for expression in E. Coli. The polypeptide so produced was a new type of t-PA lacking finger-domain, but revealed plasminogen activator activity with the function of fibrin affinity.