Loss of a consensus splice signal in a mutant immunoglobulin gene eliminates the CH1 domain exon from the mRNA

C. R. Brandt, S. L. Morrison, B. K. Birshtein, C. Milcarek

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

A series of mouse myeloma mutants, derived from a cell line of the murine MPC-11 tumor (γ2b, kappa), resemble human heavy-chain disease in their loss of an internal domain (exon). In these mutants, most of the γ2b 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) dervied 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 I17 genome-expressed γ2b constant region DNA was cloned. Sequence studies showed a deletion of 99 nucleotides around the 3' and 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.

Original languageEnglish (US)
Pages (from-to)1270-1277
Number of pages8
JournalMolecular and cellular biology
Volume4
Issue number7
DOIs
StatePublished - 1984

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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