Nature of recombination involved in excision and rearrangement of human repetitive DNA.

An alphoid-like human repetitive DNA of the Sau3A family is present extrachromosomally and in the chromosomes. In the chromosomes, the DNA is located on chromosome 11 but related sequences are present in chromosome 17. We characterized the nature of the recombination involved in the excision of the extrachromosomal DNA from chromosome 11. The results show that the recombination occurs both between the homologous subunits and between the heterologous subunits with only a 70 to 80% sequence homology among them, suggesting that a DNA structure other than a sequence homology mediates the recombination process. The same type of recombination is responsible for the rearrangement of the related sequences in chromosome 17.