Carboxy-terminal structure of the α chain of human IgA [immunoglobulin A] myeloma proteins

Prahl, James W.; Abel, Carlos; Grey, Howard M.

doi:10.1021/bi00786a012

Cited by 37 publications

(16 citation statements)

References 23 publications

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“…The third peptide (B3) that was released from Al upon cleavage of disulfide bonds was eluted from Sephadex G-25 at the same position as the C-terminal octapeptide of the a chain (D2); the electrophoretic mobility and amino acid composition of both fractions were identical. The amino acid composition and sequence of the C-terminal octapeptide of the a chain were previously reported by others (26,29). The amount of C-terminal tyrosine was lower than anticipated.…”

Section: Discussionsupporting

confidence: 70%

“…2D). Fractions D2 and B3 were eluted at the same position, had an amino acid composition (Table 1) essentially identical to each other and to the C-terminal octapeptide of the a chain described by Prahl et al (26). Homoserine was absent from both fractions.…”

Section: Resultsmentioning

confidence: 56%

“…The composition of the fraction B3 revealed the presence of eight amino acids in approximately equimolar amounts, with the exception of tyrosine (Table 1); homoserine was also absent from this fraction. The composition of fraction B3 strongly resembled that of the C-terminal octapeptide of the a chain (26). To verify the possibility that fraction B3 was derived from the C-terminal octapeptide of a chain, and to determine the origin of peptides present in fractions B3 and B2, the following steps were taken: a and J chains were totally reduced and alkylated, cleaved with CNBr, and then subjected to gel filtration on Sephadex G-25, to amino acid analysis, and to high-voltage electrophoresis.…”

Section: Resultsmentioning

confidence: 95%

“…(26) reported that cleavage of disulfide bonds, in addition to the CNBr treatment, was necessary for the release of Cterminal octapeptide from monomeric or polymeric IgA. It was suggested that the penultimate cysteine might be involved in the formation of an asymmetric intra-or inter-heavy chain disulfide bond.…”

Section: Discussionmentioning

confidence: 99%

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Site of J Chain Attachment to Human Polymeric IgA

Městecký

Schrohenloher

Kulhavy

et al. 1974

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

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A fragment containing J chain was released from human polymeric myeloma IgA protein by cyanogen bromide cleavage. The identity of the fragment was determined by its electrophoretic mobility and antigenic determinants. After purification by gel filtrations and DEAE-Sephadex chromatography, this fraction appeared similar (with respect to its amino acid and carbohydrate compositions and its peptide maps) to the J chain isolated from this IgA protein; the molecular weight was 17,000 i 100. Upon reduction and alkylation, with subsequent separation of peptides by gel filtration, three components were obtained: the largest component (molecular weight 13,400) corresponded to the N-terminal segment of J chain and contained a homoserine residue, the second corresponded to the C-terminal part of J chain with 13-18 amino acid residues, and the third corresponded to the C-terminal octapeptide of the a chain. The data indicate that J chain is attached to a chain(s) through the penultimate cysteine residue of the C-terminal octapeptide.In addition to heavy and light chains, human and animal polymeric immunoglobulins contain a polypeptide termed J chain (1-7) with a molecular weight of 15,600 4-200 (5, 8, 9). Studies of immunofluorescence and biosynthesis indicated that J chain was produced in plasma cells that synthesized IgA and IgM molecules (10-12). On the basis of the absence of J chain in monomeric and its presence in all polymeric immunoglobulins examined, its relatively large content of cysteine residues, and its disulfide bond attachment to immunoglobulin molecules, it was suggested that J chain joins the monomeric units of IgA and IgM to form, in an undefined manner, the respective polymeric molecules (13). Although the precise location of the disulfide linkages of J chain to IgA and IgM molecules has not been elucidated, studies on the products of proteolysis of these immunoglobulins strongly suggested an attachment in the Fc region of the heavy chain; the Fab and F(ab)2 fragments were devoid of J chain (14-16).It has been shown that J chain contains one methionine residue near the carboxy terminus (17). Therefore, part of the J chain linked by disulfide bonds to one or more heavy chain fragments should be present after cleavage with CNBr. This approach was applied for identification of the a-chain portion involved in the binding of J chain in a polymeric myeloma IgA. In this communication we present evidence which indicates that J chain is linked to the penultimate cysteine residue of the a chain(s). MATERIAL AND METHODSPurification and Characteristics of Polymeric IgA. Blood plasma from a patient (Fel) with IgA multiple myeloma was recalcified to remove fibrinogen, and a crude gamma globulin fraction was obtained by precipitation with ammonium sulfate to 50% saturation. The precipitate was collected by centrifugation and dialyzed against saline buffered with Tris -HCl at pH 7.4 and subsequently gel filtered through Sephadex G-200 and Sepharose 6-B as described in detail in a previous communication (18). The...

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Section: Discussionsupporting

confidence: 70%

Section: Resultsmentioning

confidence: 56%

Section: Resultsmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Site of J Chain Attachment to Human Polymeric IgA

Městecký

Schrohenloher

Kulhavy

et al. 1974

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

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“…IgA was reduced with 0.02 M dithiothreitol (Cleland's reagent, Calbiochem) and alkylated with a 10% molar excess of iodoacetamide according to the method of Prahl et al [14], Heavy and light chains were separated by column chromatography on Sephadex G-100 in 1 M acetic acid. Acetic acid was removed by lyophilization.…”

Section: Isolation Of Iga Light and Heavy Chainsmentioning

confidence: 99%

Naturally Occurring Human Antibodies with Specificity for Light Chains of Immunoglobulins

Scherz¹,

Pflugshaupt²,

Bütler³

1977

Vox Sanguinis

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Human sera of different categories were screened for antibodies against IgA. A surprisingly high incidence of antibodies was observed. All of these antibodies were of restricted specificity, i.e. able to react with one or a few individual IgAs from a panel of eight myeloma proteins used in the screening. In one serum of a patient with selective IgA deficiency an antibody against the allotype. A(2)m(l) was found. Some of the antibodies were shown to belong to the IgG class. The IgA, IgG and IgM content of the antibody-containing sera was generally increased. Two different antibodies which both reacted with the same individual IgA were studied in detail. The antigen involved could not be detected in normal Caucasian sera but was detectable in some sera of patients with IgA, IgG, IgM or IgD paraproteinemia. The antigenic site was located on the light chain of the Ig molecule but no correlation with either the light chain type or the genetically determined Inv factor was evident.

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