Fibrinogen binds to heparin: the relationship of the binding of other adhesive proteins to heparin.
The binding of heparin to fibrinogen was characterized. We have used an assay employing heparin coupled to Sepharose CL-6B to show that 125I-fibrinogen binds to heparin in a time-dependent, divalent ion-independent, saturable, and reversible manner. A total of 1.75 mg of fibrinogen could bind to 1 ml of heparin-Sepharose CL-6B with a Kd of 4.03 x 10(-7) M. Binding was completely inhibited by other adhesive proteins including fibronectin, von Willebrand factor (vWF), and vitronectin with IC50s of 7.2-8.8 microM. The binding of 125I-fibrinogen to heparin-Sepharose CL-6B was blocked by a monoclonal antibody (52k-2) and a polyclonal antibody (FK-2). 52k-2 inhibits the binding of vWF, and FK-2 blocks the binding of fibronectin to heparin-Sepharose CL-6B. It is therefore likely that fibrinogen has a heparin-binding site(s) which may have some overlap with those of other adhesive proteins, although the physiological role of the fibrinogen heparin-binding domain is uncertain at present.
Mohri
H
H
First Department of Internal Medicine, Yokohama City University School of Medicine, Japan.
Ohkubo
T
T
D000911:Antibodies, Monoclonal / Q000378:metabolism; D001667:Binding, Competitive; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D006493:Heparin / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D011485:Protein Binding; D013696:Temperature; D019096:Vitronectin; D014841:von Willebrand Factor / Q000378:metabolism
D000911:Antibodies, Monoclonal; D015815:Cell Adhesion Molecules; D005353:Fibronectins; D006023:Glycoproteins; D019096:Vitronectin; D014841:von Willebrand Factor; D005340:Fibrinogen; D006493:Heparin