Breakpoints of the Clcn4-2 evolutionary translocation in the Mus lineage. (A) The 3′end breakpoints located about 3 kb from the stop codon in exon 13 in both species (arrows) are defined as the point in each sequence where M. musculus and M. spretus diverge (dots indicate nonconserved nucleotides). (B) The 5′end breakpoints are complex and involve duplication of part of Mid1 and PAR sequences (1040 bp). Breakpoint 1 marks the distal edge of the duplicated sequences and breakpoint 2, the proximal edge located 281-bp upstream of exon 1. The first evidence of sequence homology with M. spretus is within exon 1; however, a region upstream of exon 1 may have been translocated and subsequently diverged, hence the uncertainty of this breakpoint (?). Chromosome X is shown as a black horizontal bar, chromosome 7, as a white bar, and the duplicated X region within chromosome 7 as a gray bar. Schematics are not to scale.
