Chromosomal organization of the Rhesus boxes.

The physical extension of the upstream Rhesus box (5′ toRHD) is 9145 bp (darkened bar). About 63% of the boxes' nucleotide sequence consists of repetitive DNA; the types of the repeat families are indicated. The overall homology between the upstream and downstream Rhesus box is 98.6%, but within a 1463-bp identity region (horizontal arrows), there is only a single 4-bp insertion (double vertical line). A CpG island (double-headed arrow) is located at the 3′ end and is in the downstream Rhesus box(3′ to RHD) adjacent to the SMP1 promoter.