Primary structure of the immunoglobulin J chain from the mouse.

Cann, Gordon M.; Zaritsky, Arieh; Koshland, Marian Elliott

doi:10.1073/pnas.79.21.6656

Cited by 48 publications

(29 citation statements)

References 31 publications

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“…Our model of the J chain as a single immunoglobulin-like domain contrasts with the two-domain model previously proposed by Cann et al (12). The two-domain structure was deduced from the differences observed in the properties of the amino-terminal and carboxyl-terminal halves of the J polypeptide.…”

Section: Discussioncontrasting

confidence: 41%

“…Recently, the complete primary structures of human and mouse J chains have become available from analyses of amino acid and nucleotide sequences (11)(12)(13). In the studies reported here, advantage was taken of these data to deduce the secondary structure of the J chain and to test the prediction by comparing the circular dichroism (CD) properties of the isolated J chain before and after renaturation.…”

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confidence: 99%

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Secondary structure of the immunoglobulin J chain.

Zikán¹,

Novotný²,

Trapane³

et al. 1985

Proc. Natl. Acad. Sci. U.S.A.

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J chain is a 137-residue polypeptide that is covalently linked to polymeric immunoglobulins and participates in their synthesis and transport to external secretions. To clarify these roles, the secondary structure of J chain was characterized by computer-assisted analyses of human and mouse sequences and by circular dichroism measurements of the isolated J chain. The secondary-structure profiles obtained were very similar to those of superoxide dismutase or immunoglobulin light chain variable domains, suggesting that the J chain folds into an eight-stranded antiparallel fl-barrel and should contain approximately 37% f-sheet conformation, with the rest of the structure existing as reverse turns (random coil).The circular dichroism measurements indicated that the conformation of denatured, S-carboxymethylated or S-sulfonated J chain consists of 75% random coil and 25% fl-structure.Upon reformation of disulfide bonds the percentage of Pstructure in the air-oxidized J chain increased to 34%, a value that is in good agreement with the secondary-structure analysis. Two alternative models of J-chain structure, a twodomain model [Cann, G., Zaritsky, A. & Koshland, M. E. (1982) (1,2). J chain plays a role both in the assembly of the polymers and in their subsequent transport to external secretions. Studies ofpolymer assembly have shown that the J chain is involved in the formation of the disulfide bridges that link the IgM or IgA heavy chain constant domains into closed, planar structures. The cysteine residues involved in these interchain bonds are present in the carboxyl termini of secreted ,u and a chains (3-5) but are absent from the carboxyl termini of the membrane forms of these chains (6, 7). Thus, J-chain expression may correlate with the shift from membrane-associated to secreted forms of ,u and a chains that is known to accompany synthesis of polymeric immunoglobulins (3).Studies of the selective transport of polymeric IgA and IgM into external secretions have shown that these immunoglob- To understand how the J chain performs these polymerspecific functions requires information about its three-dimensional structure. Such information has been difficult to obtain. Although the J chain is present in free form within immunoglobulin-secreting plasma cells, it is found outside these cells only as a covalently linked component of IgM and IgA molecules (3, 10). Moreover, J chain is so sequestered within the polymeric Fc structure that it is not readily accessible to conformational analyses. Isolation ofthe J chain from the polymers requires cleavage of the disulfide bonds and exposure to dissociating solvents. As a consequence all structural studies to date have been performed on denatured J chain.Recently, the complete primary structures of human and mouse J chains have become available from analyses of amino acid and nucleotide sequences (11-13). In the studies reported here, advantage was taken of these data to deduce the secondary structure of the J chain and to test the prediction by comparing the circula...

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Section: Discussioncontrasting

confidence: 41%

mentioning

confidence: 99%

Secondary structure of the immunoglobulin J chain.

Zikán¹,

Novotný²,

Trapane³

et al. 1985

Proc. Natl. Acad. Sci. U.S.A.

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“…Substitution of either of the Cys residues of the J chain involved in disulfide bond formation with the ␣-chain yielded IgA monomers with covalent J chain (20). The disulfide structure is not consistent with previous models of the J chain structure (21,22) but suggests that the J chain is positioned between two IgA dimers linked tail-to-tail. C ␣ 3 with the associated tail piece but not C ␣ 2 is required for J chain incorporation into IgA (23).…”

Section: Discussioncontrasting

confidence: 37%

Cysteine Residues Required for the Attachment of the Light Chain in Human IgA2

Chintalacharuvu

Bhola

et al. 2002

The Journal of Immunology

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In humans, there are two subclasses of IgA, IgA1 and IgA2, with IgA2 existing as three allotypes, IgA2m(1), IgA2m(2) and IgA2(n). In IgA1, Cys133 in CH1 forms the disulfide bond to the L chain. Our previous studies indicated that in IgA2 lacking Cys133, a disulfide bond forms between the α-chain and the L chain when Cys220 is followed by Arg221, but not when Cys220 is followed by Pro221, suggesting that the Cys in CH1 might be involved in disulfide bonding to the L chain. However, here we show that covalent assembly of the H and L chains in IgA2(n) requires hinge-proximal Cys241 and Cys242 in CH2 and not Cys196 or Cys220 in CH1. Using pulse-chase experiments, we have demonstrated that wild-type IgA2(n) with Arg221 and Cys241 and Cys242 assembles through a disulfide-bonded HL intermediate. In contrast, the major intermediate for IgA2 m(1) with Pro221 assembly was H2 even though both Cys241 and Cys242 were present. Only a small fraction of IgA2 m(1) assembles through disulfide-bonded HL. Overall, our studies indicate that for IgA2 covalent assembly of the H and L chains requires the hinge-proximal cysteines in CH2 and that the structure of CH1 influences the efficiency with which this covalent bond forms.

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“…Twenty micrograms of RNA was used for each sample analyzed. J chain mRNA was identified with a 1.2-kb cDNA fragment from plasmid Jc21 (45). PU.1 mRNA was identified with a 0.4-kb SacI cDNA fragment derived from pBSKS-PU.1 (46).…”

Section: Northern Blotsmentioning

confidence: 99%

“…However, some appeared not to express Ig, despite the fact that they retained the functionally assembled Ig genes (␥2b and/or ) of the plasmacytoma parent. For this reason, we analyzed a large number of these hybrids (45) to obtain a reliable estimate of this protein's rescuing function. Thirty-five continued to express Ig, as determined by ELISA, whereas ten did not (data summarized in Table I).…”

Section: The C-terminal Domain Of Oct-2 Is Required For Its Unique Fumentioning

confidence: 99%

Unique Function for Carboxyl-Terminal Domain of Oct-2 in Ig-Secreting Cells

Sharif

Radomska

Miller

et al. 2001

The Journal of Immunology

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The activity of Ig gene promoters and enhancers is regulated by two related transcription factors, Oct-1 (ubiquitous) and Oct-2 (B lineage specific), which bind the octamer motif (ATTTGCAT) present in these elements. As Ig promoter-binding factors, Oct-1 and Oct-2 each work together with a B lymphocyte-specific cofactor OCA-B/OBF-1/Bob-1 that interacts with them through their POU (DNA-binding) domains. Because both can mediate Ig promoter activity in B cells, there has been some question as to whether these two octamer-binding factors serve distinct functions in lymphocytes. We have shown previously that the silencing of B lymphocyte-specific genes in plasmacytoma × T lymphoma hybrids can be prevented by preserving Oct-2 expression. The pronounced effect of this transcription factor on the phenotype of plasmacytoma × T lymphoma hybrids established a critical role for Oct-2 not only in maintaining Ig gene expression, but in maintaining the overall genetic program of Ig-secreting cells. In the present study, we have explored the functional differences between Oct-1 and Oct-2 using chimeric Oct-1/Oct-2 proteins in cell fusion assays. Our results provide further evidence for an essential role for Oct-2 in Ig-secreting cells and identify the C-terminal domain of Oct-2 as responsible for its unique function in these cells.

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Primary structure of the immunoglobulin J chain from the mouse.

Cited by 48 publications

References 31 publications

Secondary structure of the immunoglobulin J chain.

Secondary structure of the immunoglobulin J chain.

Cysteine Residues Required for the Attachment of the Light Chain in Human IgA2

Unique Function for Carboxyl-Terminal Domain of Oct-2 in Ig-Secreting Cells

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