The interaction of fibronectin fragments with fibroblastic cells.
We have examined the interaction of the purified cell-binding domain of fibronectin with fibroblastic baby hamster kidney cells. When the cell-binding region of fibronectin is part of a large 75,000-dalton fragment, the direct binding of the tritium-labeled fragment to cells in suspension can be observed. There is a single class of 10(5) sites/cell with an apparent dissociation constant of 4 X 10(-7) M. When the cell-binding region is part of a smaller 11,500-dalton fragment, an interaction with cells can only be observed indirectly via inhibition assays. The apparent affinity of this fragment for the cell surface fibronectin receptor is low. This 11,500-dalton fragment competitively inhibits both the direct binding of soluble [3H]fibronectin to cells in suspension and the spreading of cells on fibronectin-coated substrates, suggesting that the fragment binds to the same receptor site as intact fibronectin. Possible models describing the mechanism of the interaction of fibronectin with its receptor are proposed.
Akiyama
S K
SK
Hasegawa
E
E
Hasegawa
T
T
Yamada
K M
KM
D000818:Animals; D000911:Antibodies, Monoclonal; D001665:Binding Sites; D001667:Binding, Competitive; D002460:Cell Line; D006224:Cricetinae; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D005353:Fibronectins / Q000276:immunology / Q000378:metabolism*; D006493:Heparin / Q000494:pharmacology; D006497:Heparan Sulfate / Q000494:pharmacology; D006801:Humans; D007158:Immunologic Techniques; D007668:Kidney; D007700:Kinetics; D008970:Molecular Weight; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism* / Q000494:pharmacology; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
D000911:Antibodies, Monoclonal; D005353:Fibronectins; D006493:Heparin; D006497:Heparan Sulfate; D010446:Peptide Fragments; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic; D014357:Trypsin