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. Further investigation to check this hypothesis showed that the binding of apolipoprotein A1 to the immunoaffinity support was PAI-2-independent and caused by a general surface affinity. This finding was corroborated by a study of the microtitre plate binding properties of the proteins. Pure, high molecular weight PAI 2 did not bind to apolipoprotein A1-coated wells, but the latter protein bound to coated as well as to uncoated wells. Thus, there is no evidence for a specific binding between the two proteins.
Research Laboratory of the Department of Obstetrics and Gynaecology, University Hospital, Lund, Sweden.
B
B
Astedt
I
I
Lencader
G
G
Martinsson
U
U
Kiso
A
A
Henschen
D016632:Apolipoprotein A-I / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism*; D005260:Female; D006801:Humans; D010920:Placenta / Q000098:blood supply; D017396:Plasminogen Activator Inhibitor 2 / Q000097:blood / Q000378:metabolism*; D011247:Pregnancy; D011485:Protein Binding / Q000502:physiology
D016632:Apolipoprotein A-I; D017396:Plasminogen Activator Inhibitor 2