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6kxs

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Cryo-EM structure of human IgM-Fc in complex with the J chain and the ectodomain of pIgR

6kxs, resolution 3.40Å

Structural highlights

6kxs is a 12 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	Electron Microscopy, Resolution 3.4Å
Ligands:
Experimental data:	Check to display Experimental Data
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

IGJ_HUMAN Serves to link two monomer units of either IgM or IgA. In the case of IgM, the J chain-joined dimer is a nucleating unit for the IgM pentamer, and in the case of IgA it induces larger polymers. It also help to bind these immunoglobulins to secretory component.[UniProtKB:P01592]

Publication Abstract from PubMed

Immunoglobulin M (IgM) plays a pivotal role in both humoral and mucosal immunity. Its assembly and transport depend on the joining chain (J-chain) and the polymeric immunoglobulin receptor (pIgR), but the underlying molecular mechanisms of these processes are unclear. We report a cryo-electron microscopy structure of the Fc region of human IgM in complex with the J-chain and pIgR ectodomain. The IgM-Fc pentamer is formed asymmetrically, resembling a hexagon with a missing triangle. The tailpieces of IgM-Fc pack into an amyloid-like structure to stabilize the pentamer. The J-chain caps the tailpiece assembly and bridges the interaction between IgM-Fc and the polymeric immunoglobulin receptor, which undergoes a large conformational change to engage the IgM-J complex. These results provide a structural basis for the function of IgM.

Structural insights into immunoglobulin M.,Li Y, Wang G, Li N, Wang Y, Zhu Q, Chu H, Wu W, Tan Y, Yu F, Su XD, Gao N, Xiao J Science. 2020 Feb 28;367(6481):1014-1017. doi: 10.1126/science.aaz5425. Epub 2020, Feb 6. PMID:32029689^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Li Y, Wang G, Li N, Wang Y, Zhu Q, Chu H, Wu W, Tan Y, Yu F, Su XD, Gao N, Xiao J. Structural insights into immunoglobulin M. Science. 2020 Feb 28;367(6481):1014-1017. doi: 10.1126/science.aaz5425. Epub 2020, Feb 6. PMID:32029689 doi:http://dx.doi.org/10.1126/science.aaz5425