Sequence analysis of cloned human satellite DNAs reveals nonrandom variations

We have cloned, from the genome of HeLa cells, related 1.8-kb highly repetitive EcoRI satellite II (and III) DNA family members that displayed a high degree of TaqI and HinfI variations. Comparative sequence analysis of these cloned DNAs suggests that highly repetitive satellite DNAs may have evolved and diversified from the rapid amplification of a pentameric unit (5' TTCCA 3'), by processes including random and non-random mutations. Base conservation, as well as mutational hotspots, were found associated with these related satellite II and III DNAs. The accumulation of C to G transversions within the pentamers, generating TaqI and HinfI sites, as well as C to T transitions at CpN dinucleotides, appear to be responsible for much of the microheterogeneity observed between related satellite II and III DNA family members.