Mutant Immunoglobulin Genes Have Repetitive DNA Elements Inserted into Their Intervening Sequences

The κ light chain genes from two mutant hybridoma cell lines defective in κ light chain synthesis were isolated and compared to the wild-type κ light chain gene. In each case, the mutant κ light chain genes were found to contain repetitive DNA elements in their intervening sequences that were not present in the intervening sequences of the wild-type κ light chain gene. These elements were found to be related to the genes of intracisternal A particles. These results suggest that the decreased production of κ light chain in the mutant cell lines is due to the presence of the intracisternal A particle-related genes.