Recombination between sequences in nonhomologous positions.

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Abstract
Crossing-over between the dispersed repeated sequences found in eukaryotic genomes would generate chromosomal rearrangements. The stability of the yeast [Saccharomyces cerevisiae] genome suggests the existence of some constraint on the ability of these sequences to interact by recombination. Strains were constructed with 2 alleles of the his3 gene located on different chromosomes. Gene conversion accounts for the majority of the recombination events between these genes but .apprx. 10% of the events are cross-overs that result in a reciprocal translocation. When 1 of the alleles is on an autonomously replicating centromere plasmid, recombination is 5-10-fold more frequent than when both alleles are chromosomal, suggesting that higher-order chromosome structure may play a role in restricting interchromosomal recombination. The translocation was also used to deduce the orientation of the his3 and rRNA genes relative to their centromeres.