Organization of the equine immunoglobulin constant heavy chain genes I. cε and cα genes

We provide a restriction map of the equine cε and cα genes as a molecular basis for isotype classification. Human and murine DNA probes were used for identification of homologous equine DNA sequences and for isolation of the equine cε and cα genes from a genomic DNA library. A detailed map of the equine 5′-sε/cε-sα/cα-3′ gene region was obtained. Equine cε and cα DNA probes were prepared and used for restriction analysis of immunoglobulin heavy chain gene loci from different horses. This analysis indicated the presence of only one equine cε and one cα gene in the haploid equine genome. In addition, for the equine cα gene, four haplotypes were identified according to BamHI restriction fragment length polymorphism (RFLP) of genomic DNA. The relative location of the cε and cα genes 3′ of the equine cμ and cγ genes was determined by restriction analysis of equi-murine heterohybridomas.