Evolutionary approach to the question of immunoglobulin heavy chain switching: evidence from cloned human and mouse genes.

Abstract
Cloned mouse and human H chain genes were used to identify regions of conserved homology between mouse and man, and between .mu. and .alpha. genes. Using heteroduplex mapping, coding segments for homologous domains appear to have been well conserved between the 2 spp., but the short intervening sequences that separate domains have diverged considerably. Extensive regions of homology 5'' to both .mu. and .alpha. constant region genes that are conserved between the 2 genes, and between mouse and man, are identified. These segments encompass regions in which .mu./.alpha. recombination occurs during the H chain class switch, and their extensive homology may be relevant to this process.