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PDBsum entry 3qny
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Immune system
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PDB id
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3qny
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References listed in PDB file
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Key reference
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Title
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Structure of a human iga1 FAB fragment at 1.55 å resolution: potential effect of the constant domains on antigen-Affinity modulation.
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Authors
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A.Correa,
F.Trajtenberg,
G.Obal,
O.Pritsch,
G.Dighiero,
P.Oppezzo,
A.Buschiazzo.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 2013,
69,
388-397.
[DOI no: ]
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PubMed id
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Abstract
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Despite being the most abundant class of immunoglobulins in humans and playing
central roles in the adaptive immune response, high-resolution structural data
are still lacking for the antigen-binding region of human isotype A antibodies
(IgAs). The crystal structures of a human Fab fragment of IgA1 in three
different crystal forms are now reported. The three-dimensional organization is
similar to those of other Fab classes, but FabA1 seems to be more rigid, being
constrained by a hydrophobic core in the interface between the variable and
constant domains of the heavy chain (VH-CH1) as well as by a disulfide bridge
that connects the light and heavy chains, influencing the relative
heavy/light-chain orientation. The crystal structure of the same antibody but
with a G-isotype CH1 which is reported to display different antigen affinity has
also been solved. The differential structural features reveal plausible
mechanisms for constant/variable-domain long-distance effects whereby antibody
class switching could alter antigen affinity.
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