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Title
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Location of secretory component on the Fc edge of dimeric IgA1 reveals insight into the role of secretory IgA1 in mucosal immunity.
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Authors
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A.Bonner,
A.Almogren,
P.B.Furtado,
M.A.Kerr,
S.J.Perkins.
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Ref.
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Mucosal Immunol, 2009,
2,
74-84.
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PubMed id
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Abstract
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Secretory immunoglobulin A (SIgA) is the most prevalent antibody in the human
body and a first line of defense in mucosal immunity. We located secretory
component (SC) relative to dimeric IgA1 (dIgA1) within the SIgA1 structure using
the constrained modeling of solution scattering and analytical
ultracentrifugation data. The extended solution structure of dIgA1 is largely
preserved within SIgA1. From conformational searches of SC locations, the
best-fit SC models within SIgA1 show that SC is extended along the outermost
convex edge of the Fc dimer in dIgA1. The topology of our SIgA1 structure
reveals that it is able to bind to one FcalphaRI receptor molecule. SC binding
to the Fc dimer confers protection to SIgA1 by the masking of proteolytically
susceptible surface sites from bacterial proteases in the harsh environment of
the mucosa. The models support a "zipper-like" unfolding of SC upon dIgA1 in the
formation and transportation of SIgA1 into the mucosa.
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