Plasminogen and tissue-type plasminogen activator bind to immobilized fibronectin.
Fibronectin immobilized onto polystyrene surface was found to bind plasminogen and tissue-type plasminogen activator (t-PA) but only slightly the urokinase type as determined using mono- and polyclonal antibodies against the activators. Of the defined fibronectin fragments tested, the Mr 120,000-140,000 fragment was found to bind both plasminogen and t-PA. Proteolytically modified plasminogen (Lys-plasminogen) bound considerably better than the native form (Glu-plasminogen). Experiments with 125I-plasminogen yielded Kd = 9.1 X 10(-8) M for the binding to immobilized fibronectin. The partially or completely inactive single-chain form of t-PA (pro-t-PA) bound considerably better than the activated two-chain form. Lysine at greater than 3 mM inhibited the binding of plasminogen. The interaction was independent of calcium ions. CaCl2 (greater than 0.5 mM) and NaCl (greater than 0.2 M) inhibited the binding of pro-t-PA and of t-PA. Fibronectin-bound t-PA retained its ability to activate plasminogen. The observed interactions may operate in directional proteolysis localizing plasminogen and plasminogen activator to degrade fibronectin-containing extracellular matrix including fibrin clots.
Salonen
E M
EM
Saksela
O
O
Vartio
T
T
Vaheri
A
A
Nielsen
L S
LS
Zeuthen
J
J
D000939:Epitopes / Q000032:analysis; D005353:Fibronectins / Q000378:metabolism*; D006801:Humans; D007106:Immune Sera; D007700:Kinetics; D010446:Peptide Fragments / Q000032:analysis; D010958:Plasminogen / Q000302:isolation & purification / Q000378:metabolism*; D010960:Plasminogen Activators / Q000302:isolation & purification; D011485:Protein Binding; D010959:Tissue Plasminogen Activator / Q000378:metabolism*
D000939:Epitopes; D005353:Fibronectins; D007106:Immune Sera; D010446:Peptide Fragments; D010958:Plasminogen; D010960:Plasminogen Activators; D010959:Tissue Plasminogen Activator