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.