Biomaterial Database

Looping out and deletion mechanism for the immunoglobulin heavy-chain class switch. 1988

H M Jäck, and M McDowell, and C M Steinberg, and M Wabl

Laboratory of Radiobiology and Environmental Health, University of California, San Francisco 94143.

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.

UI	MeSH Term	Description	Entries
D007143	Immunoglobulin Heavy Chains	The largest of polypeptide chains comprising immunoglobulins. They contain 450 to 600 amino acid residues per chain, and have molecular weights of 51-72 kDa.	Immunoglobulins, Heavy-Chain,Heavy-Chain Immunoglobulins,Ig Heavy Chains,Immunoglobulin Heavy Chain,Immunoglobulin Heavy Chain Subgroup VH-I,Immunoglobulin Heavy Chain Subgroup VH-III,Heavy Chain Immunoglobulins,Heavy Chain, Immunoglobulin,Heavy Chains, Ig,Heavy Chains, Immunoglobulin,Immunoglobulin Heavy Chain Subgroup VH I,Immunoglobulin Heavy Chain Subgroup VH III,Immunoglobulins, Heavy Chain
D007446	Chromosome Inversion	An aberration in which a chromosomal segment is deleted and reinserted in the same place but turned 180 degrees from its original orientation, so that the gene sequence for the segment is reversed with respect to that of the rest of the chromosome.	Inversion, Chromosome,Inversion, Chromosomal,Chromosomal Inversion,Chromosomal Inversions,Chromosome Inversions,Inversions, Chromosomal,Inversions, Chromosome
D002872	Chromosome Deletion	Actual loss of portion of a chromosome.	Monosomy, Partial,Partial Monosomy,Deletion, Chromosome,Deletions, Chromosome,Monosomies, Partial,Partial Monosomies
D002999	Clone Cells	A group of genetically identical cells all descended from a single common ancestral cell by mitosis in eukaryotes or by binary fission in prokaryotes. Clone cells also include populations of recombinant DNA molecules all carrying the same inserted sequence. (From King & Stansfield, Dictionary of Genetics, 4th ed)	Clones,Cell, Clone,Cells, Clone,Clone,Clone Cell
D004262	DNA Restriction Enzymes	Enzymes that are part of the restriction-modification systems. They catalyze the endonucleolytic cleavage of DNA sequences which lack the species-specific methylation pattern in the host cell's DNA. Cleavage yields random or specific double-stranded fragments with terminal 5'-phosphates. The function of restriction enzymes is to destroy any foreign DNA that invades the host cell. Most have been studied in bacterial systems, but a few have been found in eukaryotic organisms. They are also used as tools for the systematic dissection and mapping of chromosomes, in the determination of base sequences of DNAs, and have made it possible to splice and recombine genes from one organism into the genome of another. EC 3.21.1.	Restriction Endonucleases,DNA Restriction Enzyme,Restriction Endonuclease,Endonuclease, Restriction,Endonucleases, Restriction,Enzymes, DNA Restriction,Restriction Enzyme, DNA,Restriction Enzymes, DNA
D005796	Genes	A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.	Cistron,Gene,Genetic Materials,Cistrons,Genetic Material,Material, Genetic,Materials, Genetic
D005803	Genes, Immunoglobulin	Genes encoding the different subunits of the IMMUNOGLOBULINS, for example the IMMUNOGLOBULIN LIGHT CHAIN GENES and the IMMUNOGLOBULIN HEAVY CHAIN GENES. The heavy and light immunoglobulin genes are present as gene segments in the germline cells. The completed genes are created when the segments are shuffled and assembled (B-LYMPHOCYTE GENE REARRANGEMENT) during B-LYMPHOCYTE maturation. The gene segments of the human light and heavy chain germline genes are symbolized V (variable), J (joining) and C (constant). The heavy chain germline genes have an additional segment D (diversity).	Genes, Ig,Immunoglobulin Genes,Gene, Ig,Gene, Immunoglobulin,Ig Gene,Ig Genes,Immunoglobulin Gene
D005809	Genes, Regulator	Genes which regulate or circumscribe the activity of other genes; specifically, genes which code for PROTEINS or RNAs which have GENE EXPRESSION REGULATION functions.	Gene, Regulator,Regulator Gene,Regulator Genes,Regulatory Genes,Gene, Regulatory,Genes, Regulatory,Regulatory Gene
D005812	Genes, Switch	Genes that cause the epigenotype (i.e., the interrelated developmental pathways through which the adult organism is realized) to switch to an alternate cell lineage-related pathway. Switch complexes control the expression of normal functional development as well as oncogenic transformation.	Switch Genes,Switching Complex,Switch Complexes,Switching Complexes,Complex, Switching,Complexes, Switch,Complexes, Switching,Gene, Switch,Switch Gene
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia