B29: a member of the immunoglobulin gene superfamily exclusively expressed on beta-lineage cells.

Hermanson, Gary; Eisenberg, David; Kincade, Paul W.; Wall, Randolph

doi:10.1073/pnas.85.18.6890

Cited by 170 publications

(106 citation statements)

References 39 publications

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“…Sequencing of multiple PCR amplifications of 303.1.5.LM cDNA showed that the sequence of the 303.1.5.LM b29 cDNA was identical with that of the published wild-type b29 gene sequence (33). In addition, when we expressed one of these cloned 303.1.5.LM Ig-␤ cDNAs in the AtT20 endocrine cell line, it yielded a 29-kDa protein that reacted with our anti-Ig-␤ Ab (data not shown).…”

Section: The Sequence Of the 30315lm Mb1 And B29 Genesmentioning

confidence: 99%

Aberrant Trafficking of the B Cell Receptor Ig-αβ Subunit in a B Lymphoma Cell Line

Condon

Hourihane

Dang-Lawson

et al. 2000

The Journal of Immunology

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The B cell Ag receptor (BCR) has two important functions: first, it binds and takes up Ag for presentation to T lymphocytes; and second, it transmits signals that regulate B cell development. Normal expression of the BCR requires the association of the Ag binding subunit, membrane IgM (mIgM), with the signaling component, the Ig-αβ heterodimer. After assembly in the endoplasmic reticulum, the intact BCR travels through the secretory pathway to the cell surface. In this paper, we report two variants of the B lymphoma cell lines, WEHI 279 and WEHI 231, that have both lost the ability to express μ heavy chain and consequently do not express mIgM. However, these variants do express the Ig-αβ heterodimer. In one variant, WEHI 279*, the Ig-αβ remained trapped intracellularly in the absence of mIgM. The other variant, 303.1.5.LM, expressed an aberrantly glycosylated Ig-αβ on the cell surface that was capable of signaling after cross-linking with anti-Ig-β Abs. Further characterization uncovered a point mutation in the 303.1.5.LM mb1 gene that would change a proline for a leucine in the extracellular domain of Ig-α. The 303.1.5.LM Ig-αβ could not associate with a wild-type mIgM after μ heavy chain was reconstituted by DNA transfection. Thus, this mutation could define a region of the Ig-α polypeptide that is important for recognition by the endoplasmic reticulum quality control system, for association with glycosylating enzymes, and for the association of Ig-αβ subunits with mIgM subunits to create a complete BCR complex.

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Section: The Sequence Of the 30315lm Mb1 And B29 Genesmentioning

confidence: 99%

Aberrant Trafficking of the B Cell Receptor Ig-αβ Subunit in a B Lymphoma Cell Line

Condon

Hourihane

Dang-Lawson

et al. 2000

The Journal of Immunology

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“…During affinity maturation, the interaction of Ags with the BCR complex is presumably necessary for the selection of highaffinity Abs, which may elicit a critical BCR-signaling cascade. BCR stimulation triggers tyrosine phosphorylation of the ITAM of the B cell-specific molecules as CD79a (12) and CD79b (13), where src-type tyrosine kinases and adaptor molecules accumulate through tyrosine phosphorylation of their SH2 domains (14). The nonreceptor-type tyrosine kinase Lyn is expressed in lymphocytes and plays a role as a proximal tyrosine kinase in BCR-mediated signal transduction, including Syk tyrosine kinase, leading to the activation of Btk, PI3K, and phospholipase Cg (15).…”

mentioning

confidence: 99%

Lyn Signaling To Upregulate GANP Is Critical for the Survival of High-Affinity B Cells in Germinal Centers of Lymphoid Organs

Kuwahara

Nakaya

Phimsen

et al. 2012

The Journal of Immunology

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Signals through BCR and costimulatory molecules play essential roles in selecting high-affinity B cells with Ig V-region mutations in the germinal centers (GCs) of peripheral lymphoid organs. Lyn-deficient (lyn−/−) mice show impaired BCR signal triggering for cell proliferation and GC formation, causing hyper-IgM, and display autoimmunity after aging. In this study, we demonstrate that Lyn-mediated signaling to upregulate GANP is essential for the survival of mature GC-like (mGC) B cells with high-affinity type BCR mutations upon Ag immunization. Transgenic ganp expression into lyn−/− mice did not recover the Lyn-deficient phenotype with regard to B cell differentiation, serum Igs, and impaired GC formation in spleens after immunization with nitrophenyl-chicken γ-globulin, but it markedly rescued cell survival of mGC B cells by suppressing DNA damage, thereby increasing the frequency of the Trp33-to-Leu mutation in the IgVH-186.2 region and affinity maturation of nitrophenyl-binding B cells. GANP may play a critical role in Lyn-mediated signaling for the selection of high-affinity B cells in peripheral lymphoid organs.

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“…Compared with the ~" chains, the heterodimeric molecules have a different structural organization as they belong to the Ig supergene family (18,19,36,39). On the other hand, they both contain, in common with CD3-% -6, -~', and the 3' and 3 chains of the rat mast cell Fc receptor, a conserved sequence motif of six identically spaced cytoplasmic amino acids (36,46).…”

Section: Discussionmentioning

confidence: 99%

“…Expression of mlgM at the surface of murine plasmacytoma cells depends on its association with a disulfide-linked dimer of 34-and 39-kD proteins (20-22, 27, 36, 37) encoded by the rub-1 (18) and B29 (19) genes (23)(24)(25). Wienands et al (22) reported that the smaller 35-kD subunit in the mlgDassociated heterodimer is not equivalent to mb-I protein and that the murine mlgD receptor complex therefore differs from the mlgM complex.…”

Section: Discussionmentioning

confidence: 99%

“…These molecules were demonstrated to be newly defined B cell antigens (16) that are both membrane exposed and substrates for serineand threonine-kinase activity in vivo (15). mAb raised against a synthetic peptide (17) identified the 47-kD component as the product of the human homologue of the mb-I gene (16,18), and we have more recently found that the 37-kD subunit is encoded by the human homologue of the B29 gene (19,Mason et al,manuscript in preparation).…”

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confidence: 99%

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Comparison of human B cell antigen receptor complexes: membrane-expressed forms of immunoglobulin (Ig)M, IgD, and IgG are associated with structurally related heterodimers.

Noesel

Brouns

Schijndel

et al. 1992

The Journal of Experimental Medicine

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Snml'nal~We have recently reported that on human B lymphocytes, membrane IgM (mlgM) associates with a heterodimer of 47-and 37-kD polypeptides, the 47-kD subunit being encoded by the rob-1 gene. We show here that expression of rob-l, both at the mRNA and the protein level, is not restricted to IgM + B cells but can also be found in IgM-pre-B cells and mlgM-IgG + B cells. Membrane forms of IgD and IgG, isolated from freshly isolated human B cells and B cell lines, are expressed together with heterodimeric protein structures biochemically similar to the mlgM-associated polypeptides, and these were shown to comprise the products of the rnb-1 and B29 genes, or homologous genes. Finally, all three classes of antigen receptors are linked to protein kinases, capable ofphosphorylating the Ig-associated heterodimers. Our findings provide insight in the structural organization of the different antigen receptors on human B cells and have implications for their function.B cell ontogeny is characterized by the subsequent expression of different antigen receptors. Initially, maturation of committed progenitors to CD19+# -pre-B cells is antigen independent, but as Ig molecules appear at the cell surface, differentiation is arrested unless ligand binds to these receptors (1-4). On pre-B cells that synthesize # H chains but have not yet rearranged their L chain locus, a minority of the produced # chains is expressed at the cell membrane in association with the )~5/VpreB pseudo-L chain complex (5-9). As maturation progresses, so-called virgin B cells can be discerned that have successfully rearranged a conventional L chain gene, which enables them to express membrane IgM (mlgM) 1 as antigen receptor. On mature B cells, mlgM is coexpressed with idiotypicaUy identical mlgD molecules (10-14). Recognition of antigen elicits signals that lead to cellular proliferation and secretion of soluble forms of the receptors that can act, in concert with components of the nonspecific immunological system, as effector molecules. In t Abbreviations used in this paper: BCR, B cell receptor; B-LCL, B-lymphoblastic cell line; IPB, immunoprecipitation buffer; mlgM, membrane immunoglobulin M; RT, room temperature. these activated B cells, membrane expression oflgD is terminated. During the secondary immune response the majority of responding cells are memory B cells that express and secrete Ig of other isotypes than M and D, i.e., G, E, and A (2). Based on the qualities of their Fc portions and differences in valency, the secreted forms of the different Ig classes exhibit distinct effector functions. To date, however, it is unknown to what extent the membrane-expressed forms of the five classes of antigen receptors differ in their coupling to intraceUular signaling pathways.Recently, we have shown that mlgM on human B cells is noncovalently associated with a disulfide-linked dimer comprising glycoproteins of 47 and 37 kD (15, 16). These molecules were demonstrated to be newly defined B cell antigens (16) that are both membrane exposed and substrates f...

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B29: a member of the immunoglobulin gene superfamily exclusively expressed on beta-lineage cells.

Cited by 170 publications

References 39 publications

Aberrant Trafficking of the B Cell Receptor Ig-αβ Subunit in a B Lymphoma Cell Line

Aberrant Trafficking of the B Cell Receptor Ig-αβ Subunit in a B Lymphoma Cell Line

Lyn Signaling To Upregulate GANP Is Critical for the Survival of High-Affinity B Cells in Germinal Centers of Lymphoid Organs

Comparison of human B cell antigen receptor complexes: membrane-expressed forms of immunoglobulin (Ig)M, IgD, and IgG are associated with structurally related heterodimers.

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