Produced mainly in the liver, plasminogen is the inactive zymogen form of plasmin, and circulates in plasma in a closed conformation that cannot be activated.

Where is the source of plasminogen?

Plasminogen and tissue-type plasminogen activator

It is primarily produced by the liver. Plasminogen circulates in blood as a zymogen and can be activated to the protease plasmin by two activators named tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA).

How is plasminogen formed?

Tissue plasminogen activator (tPA) is released by endothelial cells in damaged blood vessels. tPA is a serine protease and catalyzes the conversion of plasminogen into plasmin by cleaving the bond between arginine 561 and valine 562 and removing the N-terminal portion.