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Fluorescence Biomembrane Force Probe: Concurrent Quantitation of Receptor-ligand Kinetics and Binding-induced Intracellular Signaling on a Single Cell
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Fluorescence Biomembrane Force Probe: Concurrent Quantitation of Receptor-ligand Kinetics and Binding-induced Intracellular Signaling on a Single Cell

Published on: August 4, 2015

Location of the binding site in subcomponent C1q for plasma fibronectin

K B Reid, J Edmondson

    Acta Pathologica, Microbiologica, Et Immunologica Scandinavica. Supplement
    |January 1, 1984
    PubMed

    Insights

    This study clarifies fibronectin binding to C1q, showing both globular and collagen-like regions interact. The specific binding site on C1q for fibronectin is identified within residues 81-97.

    Area of Science:

    • Immunochemistry
    • Molecular Biology
    • Protein Interactions

    Background:

    • Previous research on fibronectin (FN) and C1q interactions presented conflicting findings regarding binding sites.
    • Both globular head regions and collagen-like domains of C1q have been implicated in fibronectin binding.

    Purpose of the Study:

    • To resolve conflicting data on fibronectin binding to C1q.
    • To precisely identify the binding domains of C1q responsible for fibronectin interaction.
    • To investigate the inhibition of the C1q-fibronectin interaction by C1q digestion products.

    Main Methods:

    • 125I-labelled fibronectin binding assays were performed using immobilized intact C1q and its collagenase or pepsin digestion products.
    • Microtitre plates were used for immobilizing C1q and its fragments.
    • Inhibition assays were conducted using C1q digestion products to study the C1q-fibronectin interaction.

    Main Results:

    • The study confirmed that both globular 'head' region preparations and collagen-like region preparations of C1q can interact with fibronectin.
    • Fibronectin binding was observed with both intact C1q and its distinct digestion fragments.
    • Inhibition studies provided further evidence for the interaction sites.

    Conclusions:

    • The binding site for fibronectin on C1q is located within a region encompassing residues 81-97 of each of the three C1q chains.
    • This specific region is shared among the fragments studied, explaining the interaction.
    • The findings reconcile previous conflicting reports on C1q-fibronectin interactions.

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