Plasminogen activator inhibitor type-1 (PAI-1), a member of the serine protease inhibitor (serpin)
superfamily, is an important protein in the regulation of fibrinolysis. PAI-1 is unique among the serpins
because of its functional and conformational flexibility. PAI-1 is the most important physiological
inhibitor of both tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-
PA). Increased PAI-1 levels are associated with thrombotic events and is an established risk factor for
cardiovascular diseases. The active conformation PAI-1 inhibits its target proteinases by the formation
of a stable, inactive complex. Although PAI-1 is synthesized as an active molecule, it converts
spontaneously to an inactive, latent form that can be partially reactivated by denaturing agents. In
addition, a third conformation reacting as a non-inhibitory substrate towards various target proteinases
has been identified.
The epitope of monoclonal antibody MA-33H1F7 is predominantly composed of three residues
(Lys154/Glu130/Arg131), positioned virtually linearly in the three-dimensional structure. The epitope of the
antibody does not cover the complete alpha-helix F and turn connecting alpha-helix F and beta-strand
s3A, but is restricted to the hinge region between alpha-helix F and the main part of the PAI-1
The monoclonal antibody MA-33H1F7 is a ‘switching’ antibody, capable of inducing a non-inhibitory
substrate form of PAI-1. It was shown to inhibit PAI-1 in a dose dependent manner.
Functional studies, Immuno assays, Western blot
W: A non-reduced sample treatment and SDS-Page was used. The band size is 52 kDa (Ref.5).
FS: Antibody MA-33H1F7 functions as an antagonist. The antibody was- incubated with active PAI-1 and residual activity was measured by a functional assay (Ref.1).
For Western blotting, dilutions to be used depend on detection system applied. It is recommended that users test the reagent and determine their own optimal dilutions. The typical starting working dilution is 1:50. For functional studies, dilutions have to be optimized in user's experimental setting.