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Harvesting Murine Alveolar Macrophages and Evaluating Cellular Activation Induced by Polyanhydride Nanoparticles
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Harvesting Murine Alveolar Macrophages and Evaluating Cellular Activation Induced by Polyanhydride Nanoparticles

Published on: June 8, 2012

Recognition of nucleophile-treated alpha 2-macroglobulin by the alveolar macrophage alpha-macroglobulin . protease

J Kaplan, F A Ray, E A Keogh

    The Journal of Biological Chemistry
    |August 10, 1981
    PubMed

    Insights

    Rabbit macrophages recognize alpha 2-macroglobulin (a2M) complexed with proteases. Nucleophile treatment transforms native a2M into a form also recognized by these receptors, suggesting a conformational change.

    Area of Science:

    • Biochemistry
    • Immunology
    • Cell Biology

    Background:

    • Rabbit alveolar macrophages possess surface receptors that bind alpha 2-macroglobulin (a2M) complexed with proteases.
    • Native a2M is not recognized by these receptors.

    Purpose of the Study:

    • To investigate the mechanism by which native alpha 2-macroglobulin is converted into a form recognized by macrophage surface receptors.
    • To explore the role of nucleophilic agents in this conversion process.

    Main Methods:

    • Treatment of human alpha 2-macroglobulin with nucleophilic agents (methylamine, ammonium salts).
    • Analysis of ligand binding concentration dependency to macrophage surface receptors.
    • Comparison of binding affinities for protease-complexed a2M, nucleophile-treated a2M, and native a2M.

    Main Results:

    • Nucleophile treatment converts native alpha 2-macroglobulin into a form recognized by the same receptors that bind a2M-protease complexes.
    • The macrophage surface receptor shows similar binding affinity for both nucleophile-treated a2M and a2M-protease complexes.
    • These findings support the hypothesis that hydrolysis of an internal thiol-ester bond in a2M induces a conformational change.

    Conclusions:

    • The hydrolysis of an internal thiol-ester bond in alpha 2-macroglobulin, triggered by either proteases or nucleophilic agents, leads to a conformational alteration.
    • This conformational change exposes a binding site, enabling recognition by specific surface receptors on rabbit alveolar macrophages.

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