Intervening Sequences in Human Fetal Globin Genes
نویسندگان
چکیده
The large intervening sequences (IVSB) of three human fetal globin genes contain tracts of alternating purine-pyrimidine sequences approximately 40-60 base pairs in length which adopt left-handed Z DNA helices under the influence of negative supercoiling. The amount of negative supercoiling (-0.045) required for the rightto left-handed transitions is within the physiological range. The structural aberrations between the rightand left-handed helices were mapped by sequencing the SI nuclease cleavage sites. Twodimensional gel electrophoretic analyses of the supercoil-induced relaxation served to characterize the type and length of left-handed structure. Furthermore, binding studies with several types of antibodies confirmed the presence of left-handed helices. Since these simple sequences appear to be hotspots for recombination and gene conversion, unusual DNA conformations may participate in genetic expression.
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