Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026764 (multiple myeloma)
 36,148 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The first complete amino-acid sequence of the variable region of the gamma 3 heavy chain from a murine anti-streptococcal group A polysaccharide (A-CHO) immunoglobulin (monoclonal antibody 2S1.3) is described. Therefore, in conjunction with the previously published 2S1.3 light chain sequence, a V kappa 25 structure, the entire variable domain of this antibody has been determined. In addition, four partial amino-terminal heavy chain sequences of other antibodies with the same specificity are reported. These heavy chains share a high degree of homology with heavy chains from fructosan-binding murine myeloma proteins with the exception of those positions known to be encoded by the D (diversity) segment in germ line DNA. The light chains associated with the heavy chains reported here are products of the V kappa 25, V kappa 27, and J kappa 5 genes. Up to date three VH and four V kappa subgroups have been shown to contribute genetic material to the assembly of antibodies specific for the A-CHO. Unlike other experimental systems employing structurally completely resolved full antigens the antistreptococcal immune response uses V genes previously shown to be involved in the formation of antibodies with different specificities. This provides further experimental evidence for the physiological relevance of heavy/light chain association as a posttranscriptional diversification mechanism in the generation of the antibody repertoire in addition to those somatic diversifiers acting directly upon the genes encoding the variable regions of individual chains.
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PMID:Combinatorial diversity in the generation of antibody molecules. The complete amino-acid sequence of the variable domain of a monoclonal anti-streptococcal group A polysaccharide antibody. 353 42

The affinity maturation of antibodies is driven by somatic hypermutation which is localized to specific segments of the coding genes. The information available on this process derives from studies in vivo. With the intention of developing new approaches, we have constructed a fusion gene between a kappa chain and a selectable neomycin resistance gene, neor. The neor gene, which includes the SV40 small t intron and polyadenylation site, but not the upstream elements nor its first 12 amino acids, is an in-frame substitution of the FR2-CDR3 fragment of a rearranged V kappa OX1-J kappa 5 gene. Expression of neor activity is therefore dependent on the upstream immunoglobulin sequence. A stop codon was placed in the CDR1 region so that only mutants survive treatment with geneticin sulphate (G418). The effectiveness of the system was tested by transfecting the NS0 myeloma cell line and isolating spontaneous mutants. Neomycin-resistant clones arose at an estimated rate of 1 x 10(-8)/cell division, and over 90% were authentic structural mutants. Unlike the somatic hypermutations, the majority arose by in-frame deletions including the stop codon, although up to 30% involved a point mutation. The reporter gene was then modified by substituting all the sequences downstream of the J kappa 5 with others known to be required for full hypermutation in vivo. Different cell lines were transfected and G418-resistant clones analyzed. No significant increase in the rate of reversion or in the generation of point mutations versus deletions was detected, even using conditioned culture medium. In the presence of azacytidine however, a mutant involving multiple events (single base addition and deletion plus two point mutations) was detected. The reporter gene system therefore seems suitable to test culture conditions and modifications of the host cells aimed at the derivation of an in vitro assay of somatic hypermutation.
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PMID:A reporter gene to analyse the hypermutation of immunoglobulin genes. 778 11