Figure 5
5' and 3' splice site selection of Alu, B1, and MIR. Both Alu and B1 originated from 7SL RNA. Alu has a dimeric form with a very similar left and right arm, whereas B1 has a monomeric form similar to the left arm of the Alu element. (a) The most selected 5'ss and 3'ss within the exonized Alu element in the antisense orientation. The right and left arm are shown by boxes. The numbers within the boxes indicate positions (according to the Alu consensus sequence) in which the prevalent 3'ss and 5'ss are selected, above and below the boxes, respectively. Pictogram depiction of each splice site is shown, the consensus sequence of Alu is marked above the pictogram, and the number of times that the site was selected is shown below it. (b and c) Similar presentation as in panel a for the prevalent 5'ss and 3'ss selected in B1 and mammalian interspersed repeat (MIR) elements, respectively.