J chain

Joining chain of multimeric IgA and IgM
Identifiers
Symbols	JCHAIN ; IGCJ; IGJ; JCH
External IDs	OMIM: 147790 MGI: 96493 HomoloGene: 16958 GeneCards: JCHAIN Gene
Gene ontology Molecular function • single-stranded DNA binding • antigen binding • IgA binding • phosphatidylcholine binding • immunoglobulin receptor binding • protein homodimerization activity • peptidoglycan binding Cellular component • extracellular region • extracellular space • extracellular exosome • monomeric IgA immunoglobulin complex • dimeric IgA immunoglobulin complex • secretory IgA immunoglobulin complex • secretory dimeric IgA immunoglobulin complex • pentameric IgM immunoglobulin complex • hexameric IgM immunoglobulin complex • blood microparticle Biological process • retina homeostasis • adaptive immune response • glomerular filtration • immune response • antibacterial humoral response • positive regulation of protein oligomerization • innate immune response • positive regulation of respiratory burst Sources: Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	3512	16069
Ensembl	ENSG00000132465	ENSMUSG00000067149
UniProt	P01591	P01592
RefSeq (mRNA)	NM_144646	NM_152839
RefSeq (protein)	NP_653247	NP_690052
Location (UCSC)	Chr 4: 70.66 – 70.68 Mb	Chr 5: 88.52 – 88.53 Mb
PubMed search

Immunoglobulin M (IgM) pentameric antibody molecule (consisting of five base units).
1: Base unit.
2: Heavy chains.
3: Light chains.
4: J chain.
5: Intermolecular disulfide bonds.

The dimeric IgA molecule.
1: Heavy chains.
2: Light chains.
3: J-chain.
4: Secretory component.

A J chain is a protein component of the antibodies IgM and IgA.^[1] It is a 137 residue polypeptide,^[2] encoded by the IGJ gene.^[3][4][5]

Structure

The J Chain's molecular weight is approximately 15 kDa. It exhibits a standard immunoglobulin folding structure of two β-pleated sheets of four ribbons folded against one another. It has 8 cystine residues. Two of these residues link the α chains of IgA or the μ chains of IgM via disulfide bridges, effectively serving as the "glue" between two Fc regions of the antibody.^[6]

The J-chain shows a large degree of homology between avian and human species, suggesting that it serves an important function.^[6]

Function

The J Chain is required for IgM or IgA to be secreted into mucosa.^[2]

Because IgM and IgA are the only two types of antibody that polymerize, initial hypotheses stated that J chain was required for polymerization. However, it was subsequently found that IgM is able to polymerize in the absence of J chain as both a pentamer and a hexamer, however, both of these exist to lesser numbers in organisms lacking J chains. In such cases, there are also fewer IgA dimers.^[2]

References

1. Levinson. Medical Microbiology and Immunology (11 ed.). McGrawHill. pp. 405–6.
2. Schroeder, Harry; Wald, David; Greenspan, Neil (2008). "Chapter 4: Immunoglobulins: Structure and Function". In Paul, William. Fundamental Immunology (Book) (6th ed.). Philadelphia, PA: Lippincott Williams & Wilkins. pp. 125–151. ISBN 0-7817-6519-6.
3. Max EE, McBride OW, Morton CC, Robinson MA (Sep 1986). "Human J chain gene: chromosomal localization and associated restriction fragment length polymorphisms". Proc Natl Acad Sci U S A 83 (15): 5592–6. doi:10.1073/pnas.83.15.5592. PMC 386334. PMID 3016707.
4. Max EE, Korsmeyer SJ (May 1985). "Human J chain gene. Structure and expression in B lymphoid cells". J Exp Med 161 (4): 832–49. doi:10.1084/jem.161.4.832. PMC 2189063. PMID 2984306.
5. "Entrez Gene: IGJ immunoglobulin J polypeptide, linker protein for immunoglobulin alpha and mu polypeptides".
6. Kiyono, Hiroshi; Kunisawa, Jaw; McGhee, Jerry; Mestecky, Jiri (2008). "Chapter 31: The Mucosal Immune System". In Paul, William. Fundamental Immunology (Book) (6th ed.). Philadelphia, PA: Lippincott Williams & Wilkins. pp. 983–1030. ISBN 0-7817-6519-6.

Further reading

• Koshland ME (1986). "The coming of age of the immunoglobulin J chain.". Annu. Rev. Immunol. 3: 425–53. doi:10.1146/annurev.iy.03.040185.002233. PMID 2415140.
• Tartakoff A, Vassalli P (1980). "Plasma cell immunoglobulin M molecules. Their biosynthesis, assembly, and intracellular transport.". J. Cell Biol. 83 (2 Pt 1): 284–99. doi:10.1083/jcb.83.2.284. PMC 2111544. PMID 115892.
• Mole JE, Bhown AS, Bennett JC (1977). "Primary structure of human J chain: alignment of peptides from chemical and enzymatic hydrolyses.". Biochemistry 16 (16): 3507–13. doi:10.1021/bi00635a002. PMID 407930.
• Bastian A, Kratzin H, Eckart K, Hilschmann N (1993). "Intra- and interchain disulfide bridges of the human J chain in secretory immunoglobulin A.". Biol. Chem. Hoppe-Seyler 373 (12): 1255–63. doi:10.1515/bchm3.1992.373.2.1255. PMID 1292512.
• Frutiger S, Hughes GJ, Paquet N, et al. (1993). "Disulfide bond assignment in human J chain and its covalent pairing with immunoglobulin M.". Biochemistry 31 (50): 12643–7. doi:10.1021/bi00165a014. PMID 1472500.
• Moro I, Iwase T, Komiyama K, et al. (1990). "Immunoglobulin A (IgA) polymerization sites in human immunocytes: immunoelectron microscopic study.". Cell Struct. Funct. 15 (2): 85–91. doi:10.1247/csf.15.85. PMID 2113434.
• Alberini CM, Bet P, Milstein C, Sitia R (1990). "Secretion of immunoglobulin M assembly intermediates in the presence of reducing agents.". Nature 347 (6292): 485–7. doi:10.1038/347485a0. PMID 2120591.
• Sumi Y, Nagura H, Kaneda T, Oka T (1989). "Immunoelectron microscopical localization of immunoglobulins, secretory component and J chain in the human minor salivary glands.". J. Oral Pathol. 17 (8): 390–5. doi:10.1111/j.1600-0714.1988.tb01303.x. PMID 3146624.
• Hajdu I, Moldoveanu Z, Cooper MD, Mestecky J (1984). "Ultrastructural studies of human lymphoid cells. mu and J chain expression as a function of B cell differentiation.". J. Exp. Med. 158 (6): 1993–2006. doi:10.1084/jem.158.6.1993. PMC 2187181. PMID 6417260.
• Yasuda N, Kanoh T, Uchino H (1980). "J chain synthesis in human myeloma cells: light and electron microscopic studies.". Clin. Exp. Immunol. 40 (3): 573–80. PMC 1538946. PMID 6774844.
• Harper SJ, Allen AC, Béné MC, et al. (1995). "Increased dimeric IgA-producing B cells in tonsils in IgA nephropathy determined by in situ hybridization for J chain mRNA.". Clin. Exp. Immunol. 101 (3): 442–8. doi:10.1111/j.1365-2249.1995.tb03132.x. PMC 1553245. PMID 7664491.
• Iwase T, Saito I, Takahashi T, et al. (1994). "Early expression of human J chain and mu chain gene in the fetal liver.". Cell Struct. Funct. 18 (5): 297–302. doi:10.1247/csf.18.297. PMID 8168154.
• Harper SJ, Pringle JH, Wicks AC, et al. (1994). "Expression of J chain mRNA in duodenal IgA plasma cells in IgA nephropathy.". Kidney Int. 45 (3): 836–44. doi:10.1038/ki.1994.110. PMID 8196286.
• Bjercke S, Brandtzaeg P (1994). "Glandular distribution of immunoglobulins, J chain, secretory component, and HLA-DR in the human endometrium throughout the menstrual cycle.". Hum. Reprod. 8 (9): 1420–5. PMID 8253928.
• Bertrand FE, Billips LG, Gartland GL, et al. (1996). "The J chain gene is transcribed during B and T lymphopoiesis in humans.". J. Immunol. 156 (11): 4240–4. PMID 8666793.
• Atkin JD, Pleass RJ, Owens RJ, Woof JM (1996). "Mutagenesis of the human IgA1 heavy chain tailpiece that prevents dimer assembly.". J. Immunol. 157 (1): 156–9. PMID 8683109.
• Strausberg RL, Feingold EA, Grouse LH, et al. (2003). "Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences.". Proc. Natl. Acad. Sci. U.S.A. 99 (26): 16899–903. doi:10.1073/pnas.242603899. PMC 139241. PMID 12477932.