Table 1

Details of the different types of satellite DNA

SatelliteMinisatellite (telomeric)Minisatellite (hypervariable)Microsatellite
Other namesVariable number tandem repeats (VNTRs)Short tandem repeats (STRs)
Size of repeat unit5 to several hundred basesMainly “TTAGGG”' in humans6 to > 50 bp1 to 5 bp
Total expansion size100 kb to several Mb10–15 kb100 bp to ∼ 20 kb10 to ∼100 bp (excluding certain trinucleotide repeats)
LocationHeterochromatin, especially centromeric heterochromatinAll telomeresThroughout genome, but most clustered in telomeric regionsDistributed almost ubiquitously throughout genome
Biological functionsUnknown (probably none)Protects chromosome ends, provides means of terminal sequence replication, possible roles in chromosome pairing and cell ageingVery rare examples of expression, importance unknown. Otherwise unknown (probably none)Unknown, but may fine tune gene expression. Again trinucleotides are special case. (Contingency genes in prokaryotes)