Figure 4.

Dot plot of the human 3'RR-2 against itself and 3'RR-1. The two human 3'RR are compared to show the almost identical sequence and the palindromic structure encompassing the enhancer HS1.2 (light blue frame). Each portion of the palindrome is extended for ~3 kb. The black squares of spots indicate the presence of short stretches of DNA satellite tandem repeat. The two HS1.2 enhancers have inverted orientation in the two 3'RR as a result of the inverted orientation of the sequence internal to the palindrome. The orientation of the other enhancers is conserved and also the distances. The 20 bp repeat in dark blue appears to be larger in the 3'RR1.