Association of poly(CA).poly(TG) DNA fragments into four-stranded complexes bound by HMG1 and 2

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Science  15 Apr 1994:
Vol. 264, Issue 5157, pp. 433-436
DOI: 10.1126/science.8153633


The tandemly repeated DNA sequence poly(CA).poly(TG) is found in tracts up to 60 base pairs long, dispersed at thousands of sites throughout the genomes of eukaryotes. Double-stranded DNA fragments containing such sequences associated spontaneously with each other in vitro, in the absence of protein, forming stable four-stranded structures that were detected by gel electrophoresis and electron microscopy. These structures were recognized specifically by the nuclear nonhistone high mobility group (HMG) proteins 1 and 2 as evidenced by gel retardation. Such sequence-specific complexes might be involved in vivo in recombination or other processes requiring specific association of two double-stranded DNA molecules.