The binding of plasminogen fragments to cultured human umbilical vein endothelial cells

Glu-plasminogen, kringle 1–5, kringle 1–3; and miniplasminogen exhibited strong binding to human umbilical vein endothelial cells (HUVEC). On the other hand, no significant binding was obtained with microplasminogen and kringle 4. Kringle 1–5 and miniplasminogen, which both contained kringle 5, specifically inhibited the binding of plasminogen to HUVEC while kringle 1–3 did not. The results implied plasminogen molecule contained at least two binding sites, with which it interacted HUVEC. The stronger binding site was located in kringle 5 and the weaker one was in kringle 1–3. Kringle 4 and the active site domain exhibited no significant binding to HUVEC. The interaction of plasminogen with HUVEC is mainly through binding site on kringle 5.