Summary
Gel-filtration experiments of mixtures of functionally active and inactive forms of
plasminogen activator inhibitor (PAI) with human plasma or bovine serum albumin have
provided evidence for the existence of a discrete binding protein of PAI in plasma.
Most likely it is a glycoprotein with a molecular weight of approximately 150,000.
The data suggest that it forms a very stable complex with functionally active forms
of PAI, but not with the inactive or “latent” PAI. However, the PAI activity seems
not to be significantly altered by the interaction with the binding protein. Assuming
that a stoichiometric complex is formed, titration experiments suggest that a pool
of normal human plasma contains about 40–50 mg of PAI-binding protein liter.
Keywords
Plasminogen activator inhibitor (PAI) - Protein-protein interaction - PAI-binding
protein
