Purification and characterization of a plasminogen activator inhibitor 1 binding protein from human plasma. Identification as a multimeric form of S protein (vitronectin).

Vegf

“…Among the functional interactions of VN with proteolytic systems, binding to the serine protease inhibitor PAI-1 and to thrombin-inhibitor complexes are of major importance for regulation of hemostatic events and pericellular proteolysis. As a functional consequence, complex formation with VN does not only increase the half-life of PAI-1 in the circulation by two-to fourfold (Declerck et al 1988) but enables the active inhibitor to become stabilized at sites of vascular injury and initial platelet plug formation. PAI-1 has also been identified as "heparin cofactor" and kinetic data indicate that both, VN and heparin, drastically change the specificity of PAI-1 toward thrombin, such that this procoagulant enzyme becomes recognized and subsequently neutralized by PAI-1.…”

Phosphatidylinositol 4-Kinase (PI4K2B)

“…This dynamic conformational change displaces the RCL into the core of the protein. In the mature form, PAI-1 is a 379 amino acid protein with a molecular mass of 42.7 kD (Ginsburg et al 1986;Declerck et al 1988). Stabilization of PAI-1 by vitronectin has profound impact in understanding its role in complex diseases such as cancer.…”

A Case of Unexplained Cerebral Sinus Thrombosis in a 22-Year-Old Obese Caucasian Woman

“…19 The plasma half-life of PAI-1 has been reported to be approximately 5 to 7 minutes, 8 and the active form of PAI-1 is stabilized in the circulation by noncovalent binding to the glycoprotein vitronectin. 20 Four different conformations of PAI-1 have been described, namely, the active form that reacts with plasminogen activator, a latent form that is nonreactive but can be converted to the active form, a substrate form that can be cleaved by plasminogen activators but is noninhibitory, and the inert form of PAI-1 generated by the cleavage of the reactive site. 21 PAI-1 inhibits tPA (single-chain and 2-chain) and uPA (2-chain only) by forming a stable 1:1 complex that causes loss of activity.…”