ISSN:
1432-1211
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract The mouse B-cell lymphoma WEHI 279.1 is a tumor which synthesizes both membrane and secreted immunoglobulin M (IgM). We have immunoselected variants which fail to express the membrane form (mIgM−); the most frequently isolated phenotype is a complete loss of both membrane expression and synthesis of the μ heavy chain within the cells. We have chosen four of these mIgM − mutants for detailed molecular investigation. One of these has suffered a large deletion which covers the region of chromosome 12 containing the expressed μ gene, but three have no detectable changes in the DNA arrangement of the μ gene. All of the mutants, including the deletion mutant, synthesize 10–30% of the wild-type level of cytoplasmic μ RNA; however, none is the appropriate size for membrane μ (μm) or secreted μ (μs) message. Based on our studies of the deletion mutant, which retains its nonproductively arranged allele, at least some of these RNAs may be ‘sterile’ transcripts from the nonproductively arranged allele. However, if all of these mRNAs derive from the other allele, they represent a substantial elevation of these sterile messages relative to the wild-type level. Furthermore, the three nondeletion mutants transcribe μ RNA at a level indistinguishable from the wild type. It is likely that their defects lie in the stability, processing, or transport of the μ RNA within the nucleus. Somatic cell hybrids between P3X and the IgM− variants produced mostly mIgM− hybrids. However, a few mIgM+ hybrids were produced, suggesting that the μ− defects may be partly complemented by the P3X fusion partner.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00372292
