Nucleotide sequences of class-switch recombination region of the mouse immunoglobulin gamma 2b-chain gene

We have cloned a rearranged gamma 2b-chain gene from mouse myeloma MOPC141. Nucleotide-sequence determination demonstrated that the rearranged gamma 2b-chain gene was formed by a recombination between the region flanking the 5'-ends of the embryonic mu-chain gene and that of the gamma 2b-chain genes. Nucleotide sequences similar to the one located adjacent to the recombination site were found in other parts of the region flanking the 5'-end of the mu-chain-gene, as well as in the region flanking the 5'-end of the gamma 1-chain gene. The common sequence (GGTANNAAAGNAC) shares extensive homology with the sequence proximal to the insertion site of the bacterial insertion element IS2.