PDBsum entry 7k0c

Immune system

PDB id: 7k0c

Contents

Protein chains

534 a.a.

(+ 4 more) 227 a.a.

104 a.a.

Ligands

NAG-NAG

PDB id:

7k0c

Name:

Immune system

Title:

Structure of secretory igm core

Structure:

Polymeric immunoglobulin receptor. Chain: c. Synonym: poly-ig receptor,hepatocellular carcinoma-associated protein tb6. Engineered: yes. Immunoglobulin heavy constant mu. Chain: a, b, k, l, i, j, e, h, g, f. Synonym: ig mu chain c region,ig mu chain c region bot,ig mu chain c region gal,ig mu chain c region ou.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: pigr. Expressed in: cricetulus griseus. Expression_system_taxid: 10029. Gene: ighm. Gene: jchain, igcj, igj. Expression_system_taxid: 10029

Authors:

N.Kumar,C.P.Arthur,C.Ciferri,M.L.Matsumoto

Key ref:

N.Kumar et al. (2021). Structure of the human secretory immunoglobulin M core. Structure, 29, 564. PubMed id: 33513362 DOI: 10.1016/j.str.2021.01.002

Date:

04-Sep-20 Release date: 20-Jan-21

Protein chain

P01833  (PIGR_HUMAN) -  Polymeric immunoglobulin receptor from Homo sapiens

Seq: 764 a.a.

Struc: 534 a.a.

Protein chains

P01871  (IGHM_HUMAN) -  Immunoglobulin heavy constant mu from Homo sapiens

Seq: 474 a.a.

Struc: 227 a.a.*

Protein chain

P01591  (IGJ_HUMAN) -  Immunoglobulin J chain from Homo sapiens

Seq: 159 a.a.

Struc: 104 a.a.

* PDB and UniProt seqs differ at 15 residue positions (black crosses)

DOI no: 10.1016/j.str.2021.01.002

Structure 29:564 (2021)

PubMed id: 33513362

Structure of the human secretory immunoglobulin M core.

N.Kumar, C.P.Arthur, C.Ciferri, M.L.Matsumoto.

ABSTRACT

Immunoglobulins (Ig) A and M are the only human antibodies that form oligomers and undergo transcytosis to mucosal secretions via the polymeric Ig receptor (pIgR). When complexed with the J-chain (JC) and the secretory component (SC) of pIgR, secretory IgA and IgM (sIgA and sIgM) play critical roles in host-pathogen defense. Recently, we determined the structure of sIgA-Fc which elucidated the mechanism of polymeric IgA assembly and revealed an extensive binding interface between IgA-Fc, JC, and SC. Despite low sequence identity shared with IgA-Fc, IgM-Fc also undergoes JC-mediated assembly and binds pIgR. Here, we report the structure of sIgM-Fc and carryout a systematic comparison to sIgA-Fc. Our structural analysis reveals a remarkably conserved mechanism of JC-templated oligomerization and SC recognition of both IgM and IgA through a highly conserved network of interactions. These studies reveal the structurally conserved features of sIgM and sIgA required for function in mucosal immunity.