SEQUENCE-ANALYSIS OF CLONED HUMAN SATELLITE DNAS REVEALS NONRANDOM VARIATIONS

We have cloned, from the genome of HeLa cells, related 1.8-kb highly r epetitive EcoRI satellite II (and III) DNA family members that display ed a high degree of TaqI and HinfI variations. Comparative sequence an alysis 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. Th e accumulation of C to G transversions within the pentamers, generatin g TaqI and HinfI sites, as well as C to T transitions at CpN dinucleot ides, appear to be responsible for much of the microheterogeneity obse rved between related satellite II and III DNA family members.