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PDBsum entry 6lx3
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Immune system
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PDB id
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6lx3
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Contents |
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215 a.a.
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206 a.a.
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209 a.a.
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223 a.a.
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128 a.a.
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509 a.a.
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References listed in PDB file
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Key reference
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Title
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Structural insights into secretory immunoglobulin a and its interaction with a pneumococcal adhesin.
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Authors
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Y.Wang,
G.Wang,
Y.Li,
Q.Zhu,
H.Shen,
N.Gao,
J.Xiao.
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Ref.
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Cell Res, 2020,
30,
602-609.
[DOI no: ]
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PubMed id
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Abstract
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Secretory Immunoglobulin A (SIgA) is the most abundant antibody at the mucosal
surface. It possesses two additional subunits besides IgA: the joining chain
(J-chain) and secretory component (SC). SC is the ectodomain of the polymeric
immunoglobulin receptor (pIgR), which functions to transport IgA to the mucosa.
How the J-chain and pIgR/SC facilitate the assembly and secretion of SIgA
remains incompletely understood. Furthermore, during the infection of
Streptococcus pneumoniae, the pneumococcal adhesin SpsA hijacks pIgR/SC and SIgA
to gain entry to human cells and evade host defense. How SpsA targets pIgR/SC
and SIgA also remains elusive. Here we report a cryo-electron microscopy
structure of the Fc region of IgA1 (Fcα) in complex with the J-chain and SC
(Fcα-J-SC), which reveals the organization principle of SIgA. We also present a
structure of Fcα-J-SC complexed with SpsA, which uncovers the specific
interactions between SpsA and human pIgR/SC. These results advance the molecular
understanding of SIgA and shed light on S. pneumoniae pathogenesis.
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