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Immunoglobulin aggregation leading to Russell body formation is prevented by the antibody light chain. Blood 2009; 115:282-8. [PMID: 19822901 DOI: 10.1182/blood-2009-07-234864] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Russell bodies (RBs) are intracellular inclusions filled with protein aggregates. In diverse lymphoid disorders these occur as immunoglobulin (Ig) deposits, accumulating in abnormal plasma or Mott cells. In heavy-chain deposition disease truncated antibody heavy-chains (HCs) are found, which bear a resemblance to diverse polypeptides produced in Ig light-chain (LC)-deficient (L(-/-)) mice. In L(-/-) animals, the known functions of LC, providing part of the antigen-binding site of an antibody and securing progression of B-cell development, may not be required. Here, we show a novel function of LC in preventing antibody aggregation. L(-/-) mice produce truncated HC naturally, constant region (C)gamma and Calpha lack C(H)1, and Cmicro is without C(H)1 or C(H)1 and C(H)2. Most plasma cells found in these mice are CD138(+) Mott cells, filled with RBs, formed by aggregation of HCs of different isotypes. The importance of LC in preventing HC aggregation is evident in knock-in mice, expressing Cmicro without C(H)1 and C(H)2, which only develop an abundance of RBs when LC is absent. These results reveal that preventing antibody aggregation is a major function of LC, important for understanding the physiology of heavy-chain deposition disease, and in general recognizing the mechanisms, which initiate protein conformational diseases.
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Abstract
Studies of endogenous and engineered Ig genes in mice have begun to reveal some of the cis-acting regions that are involved in the somatic hypermutation of variable regions in vivo. These studies suggest that the initiation of transcription plays a role in this process. However, it will be difficult to identify and manipulate the individual genetic elements and the trans-acting proteins that regulate and target the mutational events using solely in vivo assays. These studies would be greatly facilitated if constructs containing the genetic elements that are essential for V-region mutation could be transfected into cultured cells and undergo high rates of V-region mutation in vitro, and if permissive and non-permissive cell lines could be identified. Such in vitro systems would also allow a detailed molecular and biochemical analysis of this process. Here, we discuss some of the in vitro systems that have been developed and use data from our own studies in cultured cells to illustrate the potential benefits of studying V-region hypermutation in model in vitro systems.
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Affiliation(s)
- N S Green
- Department of Pediatrics, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
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3
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Bachl J, Olsson C, Chitkara N, Wabl M. The Ig mutator is dependent on the presence, position, and orientation of the large intron enhancer. Proc Natl Acad Sci U S A 1998; 95:2396-9. [PMID: 9482896 PMCID: PMC19354 DOI: 10.1073/pnas.95.5.2396] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Hypermutation at the Ig loci is confined to the area between the promoter and the intronic enhancer, which includes the rearranged variable region gene segment. We identified factors that contribute to the site-specificity at the heavy chain locus. We found that distance from both the promoter and the intronic enhancer is crucial in hypermutation. The presence of the enhancer is required, and, in contrast to its definition for transcriptional activity, its effect is orientation-sensitive.
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Affiliation(s)
- J Bachl
- Basel Institute for Immunology, Postfach, CH-4005 Basel, Switzerland
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4
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Bachl J, Steinberg C, Wabl M. Critical test of hot spot motifs for immunoglobulin hypermutation. Eur J Immunol 1997; 27:3398-403. [PMID: 9464828 DOI: 10.1002/eji.1830271239] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In hypermutation at the immunoglobulin loci, some bases are much more mutable than others. The increased mutability of the hot spots has been attributed to their being embedded in short sequence motifs. Among the suggested motifs are palindromes, TAA and RGYW (i.e. A/G G C/T A/T). We have tested these proposed motifs in a transfection system in vitro, which ordinarily uses the hypermutable stop codon TAG. The stop codon TAA is not hypermutable in our system, even when embedded in the pentamer and hexamer palindromes TAATA and ATTAAT; in fact, the revertants isolated were due to deletions. Single or double base changes in an RGYW motif containing a hypermutable stop codon result in a reduction of one order of magnitude or more in point mutation frequency. When the nonamer GACTAGTAT, which includes the same RGYW motif, was moved over hundred base pairs upstream, hypermutability was reduced by an order of magnitude. Thus, while RGYW apparently is a hypermutability motif, it cannot be the sole determinant of mutability.
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Affiliation(s)
- J Bachl
- Department of Microbiology and Immunology, University of California, San Francisco 94143-0670, USA
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5
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Abstract
Hypermutation can be defined as an enhancement of the spontaneous mutation rate which the organism uses in certain types of differentiated cells where a high mutation rate is advantageous. At the immunoglobulin loci this process increases the mutation rate > 10(5)-fold over the normal, spontaneous rate. Its proximate cause is called the immunoglobulin mutator system. The most important function of this system is to improve antibody affinity in an ongoing response; it is turned on and off during the differentiation of B lymphocytes. We have established an in vitro system to study hypermutation by transfecting a rearranged mu gene into a cell line in which an immunoglobulin mutator has been demonstrated. A construct containing the mu gene and the 3' kappa enhancer has all the cis-acting elements necessary for hypermutation of the endogenous gene segments encoding the variable region. The activity of the mutator does not seem to depend strongly on the position of the transfected gene in the genome. The mutator is not active in transformed cells of a later differentiation stage. It is also not active on a transfected lacZ gene. These results are consistent with the specificity of the mutator system being maintained and make it possible to delineate cis and trans mutator elements in vitro. Surprisingly, the mutator preferentially targets G-C base pairs. Two hypotheses are discussed: (i) the immunoglobulin mutator system in mammals consists of several mutators, of which the mutator described here is only one; or (ii) the primary specificity of the system is biased toward mutation of G-C base pairs, but this specificity is obscured by antigenic selection.
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Affiliation(s)
- J Bachl
- Department of Microbiology and Immunology, University of California, San Francisco 94143-0670, USA
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6
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Wabl M, Steinberg C. Somatic hypermutability. Curr Top Microbiol Immunol 1996; 217:203-19. [PMID: 8787627 DOI: 10.1007/978-3-642-50140-1_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- M Wabl
- Department of Microbiology and Immunology, University of California, San Francisco 94143-0670, USA
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7
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Akiyama M. Late effects of radiation on the human immune system: an overview of immune response among the atomic-bomb survivors. Int J Radiat Biol 1995; 68:497-508. [PMID: 7490500 DOI: 10.1080/09553009514551491] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The studies of the late effects of atomic-bomb (A-bomb) radiation on the immune system were started about 20 years after the bombings in 1945. The most remarkable late effects of radiation are the functional and quantitative abnormalities of T and B cells in survivors exposed to high doses (> or = 1.0 Gy). Abnormalities of T-cell immunity include (1) a decreased proportion of CD3+ T cells in peripheral blood lymphocytes, particularly the proportion of CD4+ CD45RA+ naive T cells (study period 1987-91); (2) an increased frequency of CD4- and CD8- (double negative) alpha beta + T cells (1987-91); and (3) functional defects in T-cell responses to mitogens and alloantigens (1974-85). B-cell abnormalities include: (1) a significant increase in the proportion of B cells among peripheral lymphocytes (1987-91); (2) an increase in serum immunoglobulin A levels in females and immunoglobulin M and the incidence of rheumatoid factor in both sexes (1987-89); and (3) an increased level of anti-Epstein-Barr virus antibody titer (1987-90). In contrast, suggestive (0.05 < p < 0.1) or not significant (p > 0.1) dose effects were observed for the number and function of natural killer cells (1983-91), and benign monoclonal gammopathy (1979-87). In addition, studies initiated sooner after the bombing such as the incidence of autoimmune diseases (1958-87), systemic bacterial infections (1954-67), and granulocyte functions (1947-79) also show little dose-effects. Thus, A-bomb radiation induced the alteration of the balance/interaction between the T- and B-cell subsets--specifically, a decrease in the T-cell population and an increase in the B-cell population in the periphery.
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Affiliation(s)
- M Akiyama
- Department of Radiobiology, Radiation Effects Research Foundation, Hiroshima, Japan
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8
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Jäck HM, Beck-Engeser G, Lee G, Wofsy D, Wabl M. Tumorigenesis mediated by an antigen receptor. Proc Natl Acad Sci U S A 1992; 89:8482-6. [PMID: 1528851 PMCID: PMC49944 DOI: 10.1073/pnas.89.18.8482] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The heavy chain variable region of the immunoglobulin receptors on cells of the B lymphoma NYC are almost identical to that of other independent B-cell tumors of B/W mice. NYC IgM binds a viral antigen produced by the tumor cells; and despite extensive screening, immunoglobulin-negative variants were never found in the NYC cells, suggesting that NYC loses the capacity to grow in culture when it does not synthesize surface immunoglobulin. These findings indicate that the interaction of endogenous antigen with surface IgM continuously stimulates growth and, thus, that the tumorigenesis of B lymphomas in B/W mice is mediated by antigen receptors.
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MESH Headings
- Animals
- Antigens, Viral/immunology
- Base Sequence
- Cell Division
- Gene Rearrangement, B-Lymphocyte, Heavy Chain
- Gene Rearrangement, B-Lymphocyte, Light Chain
- Genes, Immunoglobulin
- Immunoglobulin Variable Region/genetics
- Lymphoma, B-Cell/microbiology
- Lymphoma, B-Cell/pathology
- Mice
- Molecular Sequence Data
- Receptors, Antigen, B-Cell/physiology
- Retroviridae/immunology
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Affiliation(s)
- H M Jäck
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153
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9
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Umeki S, Kyoizumi S, Kusunoki Y, Nakamura N, Sasaki M, Mori T, Ishikawa Y, Cologne JB, Akiyama M. Flow cytometric measurements of somatic cell mutations in Thorotrast patients. Jpn J Cancer Res 1991; 82:1349-53. [PMID: 1778756 PMCID: PMC5918347 DOI: 10.1111/j.1349-7006.1991.tb01804.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Exposure to ionizing radiation has long been well-recognized as a risk factor for cancer development. Since ionizing radiation can induce mutations, an accurate way of measuring somatic mutation frequencies could be a useful tool for evaluating cancer risks. In the present study, we have examined in vivo somatic mutation frequencies at the erythrocyte glycophorin A (GPA) and T-cell receptor (TCR) loci in 18 Thorotrast patients who have been continuously irradiated with alpha-particles emitted from the internal deposition of thorium dioxide and who thus have increased risks of certain malignant tumors. When compared with controls, the results showed a significantly higher frequency of mutants at the lymphocyte TCR loci but not at the erythrocyte GPA loci in the Thorotrast patients. The discrepancy between the results of the two assays is discussed.
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Affiliation(s)
- S Umeki
- Department of Radiobiology, Radiation Effects Research Foundation, Hiroshima
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Kyoizumi S, Akiyama M, Hirai Y, Kusunoki Y, Tanabe K, Umeki S. Spontaneous loss and alteration of antigen receptor expression in mature CD4+ T cells. J Exp Med 1990; 171:1981-99. [PMID: 1972177 PMCID: PMC2187968 DOI: 10.1084/jem.171.6.1981] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The TCR/CD3 complex plays a central role in antigen recognition and activation of mature T cells, and, therefore, abnormalities in the expression of the complex should induce unresponsiveness of T cells to antigen stimulus. Using flow cytometry, we detected and enumerated variant cells with loss or alteration of the surface TCR/CD3 expression among human mature CD4+ T cells. The presence of variant CD4+ T cells was demonstrated by isolating and cloning them from peripheral blood, and their abnormalities can be accounted for by alterations in TCR expression such as defects of protein expression and partial protein deletion. The variant frequency in peripheral blood increased with aging in normal donors and was highly elevated in patients with ataxia telangiectasia, an autosomal recessive inherited disease with defective DNA repair and variable T cell immunodeficiency. These findings suggest that such alterations in TCR expression are induced by somatic mutagenesis of TCR genes and can be important factors related to age-dependent and genetic disease-associated T cell dysfunction.
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MESH Headings
- Adult
- Antibodies, Monoclonal
- Antigens, Differentiation, T-Lymphocyte/biosynthesis
- Antigens, Differentiation, T-Lymphocyte/genetics
- Blotting, Southern
- CD3 Complex
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- CD4-Positive T-Lymphocytes/ultrastructure
- Cell Separation
- Child
- Chromosome Aberrations
- Clone Cells
- Electrophoresis, Polyacrylamide Gel
- Flow Cytometry
- Gene Expression
- Gene Rearrangement
- Humans
- Immune System Diseases/immunology
- Precipitin Tests
- Receptors, Antigen, T-Cell/biosynthesis
- Receptors, Antigen, T-Cell/genetics
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Affiliation(s)
- S Kyoizumi
- Department of Radiobiology, Radiation Effects Research Foundation, Hiroshima, Japan
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French DL, Laskov R, Scharff MD. The role of somatic hypermutation in the generation of antibody diversity. Science 1989; 244:1152-7. [PMID: 2658060 DOI: 10.1126/science.2658060] [Citation(s) in RCA: 239] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The immune system is capable of establishing an enormous repertoire of antibodies before its first contact with antigen. Most antibodies that express germ-line sequences are of relatively low affinity. Once antigen enters the system, it stimulates a somatic mutational mechanism that generates antibodies of higher affinity and selects for the expression of those antibodies to produce a more effective immune response. The details of the mechanism and regulation of somatic hypermutation remain to be elucidated.
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Affiliation(s)
- D L French
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461
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de Jong D, Voetdijk BM, van Ommen GJ, Kluin PM. Alterations in immunoglobulin genes reveal the origin and evolution of monotypic and bitypic B cell lymphomas. THE AMERICAN JOURNAL OF PATHOLOGY 1989; 134:1233-42. [PMID: 2547318 PMCID: PMC1879944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
During progression of B-lymphoproliferative disorders (B-LPD), increasing divergence can be detected in histology, cytogenetics, and clinical behavior. To investigate genomic tumor cell heterogeneity, 50 biopsies of 21 patients with B-LPD of different histogenetic origin were studied for changes in the immunoglobulin gene structure during follow-up study. Ig-heavy chain (IgH) gene alterations were analyzed by Southern blotting using a panel of eight endonucleases. Ig-light chain (IgL) genes and the translocation of the bc 1-2 gene involved in t(14;18) were also studied. In seven of nine follicular lymphomas, most alterations suggested mutations in the IgH genes. Conservation of most restriction sites and of the t(14; 18) breakpoint confirmed the monoclonal origin in these tumors. Also, in two of three diffuse follicle center cell lymphomas (CLL) and in each of four immunocytomas, IgH alterations were found. In contrast, clonal changes were absent in three centrocytic lymphomas and two cases of CLL. In two follicular lymphomas with bitypic IgL expression, a common origin with subsequent divergence of the two constituents, rather than true biclonality, was indicated by the Ig gene structures. No relation was found between the frequency of somatic mutations and histologic signs of progression. These data indicate that somatic hypermutation in IgH genes is related to the histogenesis of the B-LPD and reflect the physiology of their benign counterparts in normal B cell development.
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Affiliation(s)
- D de Jong
- Laboratory of Pathology, University Medical Centre, Leiden, The Netherlands
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13
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Abstract
When termination codons were introduced into exons of the gene for Ig mu chain, steady-state levels of mu mRNA were reduced, both at the pre-B cell stage and at the plasma cell stage. A termination codon in the variable region gene segment and a termination codon in the second exon of the constant region gene segment had effects of similar magnitude. When the termination codon was deleted, the original level of mRNA was restored. The rate of mu gene transcription was the same whether or not a termination codon was present. Therefore, the termination codons must reduce the amount of the mRNA by reducing its stability. Since the introduced termination codons prematurely terminate translation and, in so doing, change the ribosome load on the mRNA, we conclude that mu mRNA stability is conferred in part by ribosomal protection from enzymatic degradation. We propose that the differences in mu mRNA stability during B lymphocyte differentiation are due to different amounts of ribosomes available for translation.
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Affiliation(s)
- H M Jäck
- Laboratory of Radiobiology and Environmental Health, University of California, San Francisco 94143-0750
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14
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Pollock RR, French DL, Gefter ML, Scharff MD. Identification of mutant monoclonal antibodies with increased antigen binding. Proc Natl Acad Sci U S A 1988; 85:2298-302. [PMID: 3267219 PMCID: PMC279978 DOI: 10.1073/pnas.85.7.2298] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Sib selection and an ELISA have been used to isolate hybridoma subclones producing mutant antibodies that bind antigen better than the parental monoclonal antibody. Such mutants arise spontaneously in culture at frequencies of 2.5-5 X 10(-5). The sequences of the heavy and light chain variable regions of the mutant antibodies are identical to that of the parent and the Ka values of the mutants and the parent are the same. The increase in binding is associated with abnormalities of the constant region polypeptide and probably reflect changes in avidity of these antibodies.
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Affiliation(s)
- R R Pollock
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461
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15
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Jäck HM, McDowell M, Steinberg CM, Wabl M. Looping out and deletion mechanism for the immunoglobulin heavy-chain class switch. Proc Natl Acad Sci U S A 1988; 85:1581-5. [PMID: 2830623 PMCID: PMC279817 DOI: 10.1073/pnas.85.5.1581] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
In the mouse pre-B-cell line 18-81, cells can switch production in vitro from immunoglobulin mu chain to gamma 2b chain. The gene encoding the gamma 2b chain is created by a rearrangement of the mu gene. This rearrangement always takes place within a homolog. In cells with a gamma 2b gene, most of the time the gene segment encoding the constant region of the mu chain is deleted, but often the rearrangement leads to cells that produce no immunoglobulin, and all DNA sequences are retained. The latter result is due to an inversion. Inversions exclude the unequal sister chromatid exchange model of the heavy-chain class switch. Looping out is an intermediate step in the process of generating an inversion. Our findings demonstrate that the switch rearrangement occurs by looping out and deletion.
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Affiliation(s)
- H M Jäck
- Laboratory of Radiobiology and Environmental Health, University of California, San Francisco 94143
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