On the affinity between the plasminogen activator inhibitor type 2 and apolipoprotein A1.

The plasminogen activator inhibitor type 2 (PAI-2) is present in its high molecular weight, glycosylated form in pregnancy plasma. When the protein was purified from retroplacental blood by immunoaffinity chromatography on a PAI-2 antibody column and the retained material was further fractionated by gel filtration chromatography, it was always contaminated by apolipoprotein A1, the latter protein being identified by its N-terminal sequence, molecular weight in SDS-PAGE and immunological properties. The co-purification of the two proteins seemed to indicate a strong affinity between them, suggesting apolipoprotein A1 to be a carrier protein for this PAI-2 form.

Identity between the placental protein PP10 and the specific plasminogen activator inhibitor of placental type PAI-2.

The highly specific plasminogen activator inhibitor of placental type, PAI-2, occurs in the placenta in a low molecular mass form of 46.6 kDa, and in pregnancy plasma in a (possibly glycosylated) high molecular mass form of 60 kDa. Extensive knowledge is available about the functional properties of PAI-2 as a plasminogen activator inhibitor and about its molecular biology and regulation.

Determination of intermediates, products and cleavage site in the reaction between plasminogen activator inhibitor type-2 and urokinases.

Several specific inhibitors for plasminogen activators have been isolated from various organs and cell lines, those from human placenta and the human monocyte-like cell line U-937 being virtually identical. The reaction between this type of inhibitor, designated as type-2, and high-Mr and low-Mr urokinase-type plasminogen activators was followed by reversed-phase high-performance liquid chromatography and gel electrophoresis. The components, their stable complexes and their dissociation and cleavage products could be clearly identified in both systems.