Mutations, duplication, and deletion of recombined switch regions suggest a role for DNA replication in the immunoglobulin heavy-chain switch

UMMS Affiliation

Department of Molecular Genetics and Microbiology

Publication Date


Document Type



Animals; Base Sequence; Chromosome Deletion; DNA; *DNA Replication; *Genes, Immunoglobulin; Immunoglobulin Switch Region; Mice; Molecular Sequence Data; Mutation; Recombination, Genetic; Restriction Mapping


Life Sciences | Medicine and Health Sciences | Women's Studies


The heavy-chain switch from immunoglobulin M (IgM) expression to IgA expression is mediated by a recombination event between segments of DNA called switch regions. The switch regions lie two to six kilobases upstream of the mu and alpha constant region coding segments. Switch recombination to IgA expression results in a recombinant mu-alpha switch region upstream of the expressed alpha constant region gene. We have characterized the products of switch recombination by a lymphoma cell line, I.29. Two sets of molecular clones represent the expected products of simple mu to alpha switches. Five members of a third set of molecular clones share the same recombination site in both the mu and the alpha switch regions, implying that the five molecular clones were derived from a single switch recombination event. Surprisingly, the five clones fall into two sets of sequences, which differ from each other by several point mutations and small deletions. Duplication of switch region sequences are also found in these five molecular clones. An explanation for these data is that switch recombination involves DNA synthesis, which results in nucleotide substitutions, small deletions, and duplications.

DOI of Published Version



Mol Cell Biol. 1989 May;9(5):1850-6.

Journal/Book/Conference Title

Molecular and cellular biology

Related Resources

Link to article in PubMed

PubMed ID