Plasminogen (Glu-plasminogen) (PLG)

Glu-plasminogen is the native, full-length zymogen form of plasminogen, a 92-kDa glycoprotein synthesized primarily in the liver and circulating in human plasma [1][2]. It is characterized by a glutamic acid residue at its N-terminus and exists in a closed, spiral conformation that is relatively resistant to activation [3]. Upon binding to fibrin or cell surface receptors, it undergoes a conformational change to an open form, which is then cleaved by activators like tissue-type plasminogen activator (tPA) or urokinase (uPA) to form the active serine protease, plasmin [4][5]. Plasmin plays a vital role in fibrinolysis by degrading fibrin clots, and it also participates in wound healing, cell migration, and tissue remodeling [2][5]. In clinical practice, Glu-plasminogen is the target of thrombolytic drugs that accelerate its conversion to plasmin to dissolve life-threatening blood clots in conditions like stroke or heart attack [7]. Additionally, purified human plasminogen is used as replacement therapy for patients with congenital plasminogen deficiency type 1, a rare genetic disorder that leads to the formation of fibrin-rich pseudomembranous lesions [6]. Conversely, antifibrinolytic agents like tranexamic acid bind to the kringle domains of Glu-plasminogen to prevent its activation and reduce surgical bleeding [8].

Other names

Glu-plasminogenNative plasminogenPLGPlasminogen

The primary mechanism involves the proteolytic cleavage of the Arg561-Val562 bond in Glu-plasminogen by activators such as tissue-type plasminogen activator (tPA) or urokinase to generate active plasmin for fibrinolysis [1][5]. Antifibrinolytic drugs like tranexamic acid competitively inhibit this process by binding to the lysine-binding sites within the kringle domains of Glu-plasminogen, preventing its association with fibrin [8]. Replacement therapy restores physiological levels of the zymogen in deficient individuals to maintain normal mucosal and systemic fibrinolysis [6].