Title: The distal hinge of the reactive site loop and its proximity - A target to modulate plasminogen activator inhibitor-1 activity
Authors: Bijnens, AP
Gils, Ann
Stassen, JM
Komissarov, AA
Knockaert, I
Brouwers, E
Shore, JD
Declerck, Paul # ×
Issue Date: Nov-2001
Publisher: Amer soc biochemistry molecular biology inc
Series Title: Journal of Biological Chemistry vol:276 issue:48 pages:44912-44918
Abstract: The serpin plasminogen activator inhibitor type 1 (PAI-1) plays a regulatory role in various physiological processes (e.g. fibrinolysis and pericellular proteolysis) and forms a potential target for therapeutic interventions. In this study we identified the epitopes of three PAI-1 inhibitory monoclonal antibodies (MA-44E4, MA-42A2F6, and MA-56A7C10). Differential cross-reactivities of these monoclonals with PAI-1 from different species and sequence alignments between these PAI-1s, combined with the three-dimensional structure, revealed several charged residues as possible candidates to contribute to the respective epitopes. The production, characterization, and subsequent evaluation of a variety of alanine mutants using surface plasmon resonance revealed that the residues His(185), Arg(186), and Arg(187) formed the major sites of interaction for MA-44E4. In contrast, the epitopes of MA-42A2F6 and MA-56A7C10 were found to be conformational. The epitope of MA-42A2F6 comprises residues Lys(243) and Glu(350), whereas the epitope of MA-56A7C10 comprises residues Glu(242), Lys(243), Glu(244), Glu(350) Asp(355) and Arg(356). The participation of Glu(350), Asp(355), and Arg(356) provides a molecular explanation for the differential exposure of this epitope in the different conformations of PAI-1 and for the effect of these antibodies on the kinetics of the formation of the initial PAI-1-proteinase complexes. The localization of the epitopes of MA-44E4, MA42A2F6, and MA-56A7C10 elucidates two previously unidentified molecular mechanisms to modulate PAI-1 activity and opens new perspectives for the rational development of PAI-1 neutralizing compounds.
ISSN: 0021-9258
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory for Pharmaceutical Biology (-)
× corresponding author
# (joint) last author

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