Higher order structure of β-satellite repeats. β-satellites are organized into super-repeat structures consisting of two β-satellite segments flanking an Alu/LTR middle portion. The organization of each of the three “superstructures” is drawn to scale with reference to the positions of the repeats in GenBank (accession no. AC004004). The total length of each of the three segments in bp is indicated beside each segment. Calculation of length of the β-satellite flanks did not include Alu and LINE elements. This is especially evident for the structure located at positions 140–160, in which an L1PA5 element has integrated.