Conserved organization of the murine immunoglobulin ε gene region: Restriction endonuclease maps and switch-region nucleotide sequence

Various inbred mouse strains showed remarkable conservation of organization in the ε germline region as determined by restriction mapping. Restriction fragment length polymorphisms (RFLP) were seen in the ε gene region for only two of eight restriction enzymes tested. Furthermore, the RFLP did not correlate with the IgE-response phenotype for the murine strains SJL, SJA, C57BL/6, BALB/c, A/ST, and A/J. The IgE class-switch region (Sε) DNA from an SJL genomic clone was sequenced and was compared with Sε sequences from BALB/c mice. These Sε sequences were at least 95% homologous. Most of the Sε sequence differences observed between the two strains were single base pair substitutions, deletions, or insertions. The largest difference between the Sε sequences resulted from an insertion of seven contiguous bases seen in the SJL Sε region.