Molecular analysis of two recombinant mouse strains with crossovers in the E alpha recombination hot spot.

Recombination in the E alpha gene of the mouse major histocompatibility complex has been found to occur only in mice derived from crosses between strains with the k and p haplotypes. In the present paper the crossover sites of six additional strains were examined by RFLP analysis. These recombinant strains were derived from crosses between strains (B10.RPD1, B10.RPD2) with crossovers in the E alpha gene and B10.M (H-2f). Four have crossover sites between the E alpha gene and the S region. One recombinant (B10.RFD7) also crossed over within the E alpha gene and a second (B10.RPF1) crossed over within a segment located to the left of the E alpha gene. This study suggests that the DNA sequence responsible for recombination in the E alpha gene is also present in the B10.RPD1 and B10.RPD2 recombinant strains.