Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A procedure is described for the isolation of highly purified heavy-chain immunoglobulin mRNAs from a variety of mouse plasmacytomas (IgA, IgG, and IgM producers). The use of fresh tissue and the rapid isolation and direct extraction of membrane-bound polyribosomes were found to be essential in obtaining large quantities of undegraded heavy-chain mRNAs. The individual mRNAs were purified by two cycles of oligo(dT)-cellulose chromatography, sodium dodecyl sulfate--sucrose gradient centrifugation, and electrophoresis on 98% formamide containing polyacrylamide gels. When added to a cell-free protein-synthesizing system from wheat germ, the MPC-11 gamma2b and H2020 alpha heavy-chain mRNAs efficiently directed the synthesis of a predominant product of 55 000 molecular weight, while the synthesis of a 70 000 dalton protein in addition to other lower molecular weight polypeptides were observed with MOPC 3741 mu mRNA. All of these proteins were immunoprecipitable with class-specific heavy-chain antisera, and in the case of the gamma2b in vitro products good correspondence in a comparative trypsin--chymotrypsin fingerpring with in vivo labeled gamma2b heavy chain was observed. The gamma2b and a alpha heavy-chain mRNAs possessed a chain length of approximately 1800 nucleotides and the mu mRNA a size of approximately 2150 nucleotides when examined under stringent denaturation conditions. The purities of the alpha, gamma2b, and mu mRNAs were estimated to be 60--80%, 50--70%, and 50--83%, respectively, on the basis of their hybridization rates with cDNA probes in comparison to mRNA standards of known complexity. Heavy-chain mRNAs of the same class isolated from different mouse strains (Balb/C or NZB) display no detectable sequence differences in cross hybridization experiments, even though the cDNA--mRNA hybrids are submitted to stringent S1 nuclease digestion. These results indicate that allotypic determinants represent only a minor fraction of the heavy-chain constant region sequence in the mouse.
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PMID:Isolation, purification, and properties of mouse heavy-chain immunoglobulin mRNAs. 41 5

Analysis of the heat-shock response in murine plasmacytomas reveals that, as demonstrated previously for the MPC-11 cell line, the genes coding for the 68-kilodalton heat-shock protein (hsp-68) are not expressed upon heat shock or sodium arsenite treatment. Noninduction is unique to the normally coordinated set of three hsp-68 genes since at least two other heat-shock protein genes (hsp-70 and hsp-89) are properly induced. No other lymphoid cell line was found to possess silent hsp-68 genes. Cell lines examined included a T lymphoma, a pre-B lymphocyte, and a non-B-non-T tumor cell line, as well as an Ig-nonproducing myeloma of undetermined differentiated status. Nonexpression is strain-independent as observed in BALB/c and C3H plasmacytomas. Based on S1 nuclease analysis using a cloned genomic hsp-68 probe, nonexpression is caused by the absence of hsp-68 mRNA following heat shock. A time-course experiment suggests that rapid degradation of mRNA does not occur, implying that the block is most likely at the transcriptional level. Southern blot analysis does not indicate any minor deletions around the region of transcription initiation, at least in the probed hsp-68 gene. These results suggest that the absence of hsp-68 gene expression may be a reflection of the differentiated and (or) transformed state of murine plasma cells, possibly through the absence or deregulation of a regulatory factor required for induction of heat-shock genes.
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PMID:Murine plasmacytomas constitute a class of natural heat-shock variants in which the major inducible hsp-68 gene is not expressed. 303 May 21

A series of mouse myeloma mutants, derived from a cell line of the murine MPC-11 tumor (gamma 2b, kappa), resemble human heavy-chain disease in their loss of an internal domain (exon). In these mutants, most of the gamma 2b CH1 exon was present in the nuclear RNA but was removed during splicing to form the mature cytoplasmic RNA. Amino acid sequence studies of one mutant (10.1) are consistent with the loss of the complete CH1 domain. A second mutant cell line (I17) derived from 10.1 and containing the same CH1 alteration was shown by S1 nuclease protection experiments to have an additional mRNA deletion spanning the CH2-CH3 domain boundary. This second deletion was shown to result from a genomic alteration that provided a marker for the isolation of the expressed H-chain allele. To determine the basis of the CH1 splicing defect, the 117 genome-expressed gamma 2b constant region DNA was cloned. Sequence studies showed a deletion of 99 nucleotides around the 3' end of the CH1 domain, which removed the splice site and flanking DNA, apparently causing the aberrant splicing of the RNA transcript. The sequence deleted in the mutant is flanked by short repeats of the octameric sequence CCAGCCAG in the wild-type gene. In the mutant, one copy of the repeat, in addition to the sequences between the repeats, has been lost.
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PMID:Loss of a consensus splice signal in a mutant immunoglobulin gene eliminates the CH1 domain exon from the mRNA. 609 57