Kringles of the plasminogen--prothrombin gene family share conformational epitopes with recombinant apolipoprotein (a): specificity of the fibrin-binding site.
Monoclonal antibodies directed against recombinant apolipoprotein (a) (r-apo(a)) lacking plasminogen-like KIV-2 repeats were used to identify structurally related conformational epitopes in various members of the plasminogen-prothrombin gene family. A number of procedures including a fibrin-binding inhibition immunoassay and surface plasmon resonance studies were used. Two antibodies (A10.1 and A10.4) recognised common conformational structures in r-apo(a), prothrombin, factor XII, plasminogen and its tissue-type and urokinase-type activators. In contrast, two other antibodies recognised specifically an epitope comprising residues of the lysine-binding site (A10.2) or close to it (A10.5) and inhibited the fibrin-binding function of r-apo(a) (IC(50)=36 pmol/l and 9.76 nmol/l, respectively). Interestingly, these antibodies distinctly recognised the elastase-derived fragments of plasminogen K4 (A10.2) and K1+2+3 (A10.5) without affecting plasminogen binding to fibrin. These results suggest that highly conserved conformational regions are common to various proteins of the plasminogen-prothrombin gene family and are in agreement with the concept that these proteins constitute a monophyletic group derived from an ancestral gene.
Dominguez
M
M
Institut National de la Santé et de la Recherche Médicale, INSERM U.460, Plasminogen Activation in Cardiovascular Remodeling, Faculté Xavier Bichat, Paris, France.
Rojas
G
G
Loyau
S
S
Bazurco
M
M
Sorell
L
L
Anglés-Cano
E
E
D000911:Antibodies, Monoclonal / Q000276:immunology; D000915:Antibody Affinity; D001054:Apolipoproteins A / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D001665:Binding Sites; D015374:Biosensing Techniques; D003429:Cross Reactions; D005337:Fibrin / Q000737:chemistry*; D007118:Immunoassay; D018082:Kringles; D010958:Plasminogen / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D011487:Protein Conformation; D011516:Prothrombin / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D011994:Recombinant Proteins / Q000276:immunology; D020349:Surface Plasmon Resonance
D000911:Antibodies, Monoclonal; D001054:Apolipoproteins A; D011994:Recombinant Proteins; D011516:Prothrombin; D005337:Fibrin; D010958:Plasminogen