Constrained exchange model
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Although Wyman and White isolated the first Restriction Fragment Length Polymorphisms, or RFLPs (Wyman et al., 1980), Alec Jeffreys and colleagues are credited to contributing much to the field through further elaboration on Wyman and White's research. Jeffreys and colleagues worked with myoglobin to isolate minisatellites, and speculated how they might be made. They favored the “constrained exchange model” of formation, involving the “x sequence”, a unified DNA sequence that specifically aligns with myoglobin repeat sites over a 10-15 base pair region consisting of GGGCAGGAXG. The x sequence binds to endonuclease V, which unravels and dislodges a portion of DNA causing a section to be single stranded. This essentially creates a Holiday junction, which is a migrating annex between two homologous sequences of DNA. When the dislodged DNA has been synthesized for repair and ligated back to the strand, this creates the short tandem repeat unit which is then amplified, producing the minisatellite (Jeffreys et al., 1985).
[edit] References
- Alec J. Jeffreys, Victoria Wilson & Swee Lay Thein, 1985. Hypervariable 'minisatellite' regions in human DNA. Nature 314: 67-73
- Arlene R. Wyman & Ray White, 1980. A highly polymorphic locus in human DNA. Proc. Natl. Acad. Sci. USA 77: 6754-6758
