Nucleic acid cruciform structure

Until rather recently there had been little to indicate that DNA actually assumes cruciform conformations in cells. However, strong experimental evidence suggests that some cruciform structures do form naturally.380 Their formation from palindromic DNA [like the formation of Z-DNA from (G + C)-rich sequences] is a way of relieving torsional strain induced by super-coiling. Whether or not cruciform structures occur frequently within cells, there is no doubt that palindromic sequences are of great importance in the interaction of nucleic acids with symmetric dimeric and tetrameric protein molecules such as the gene repressor protein shown in Fig. 5-35.381-383... 

Creutzfeldt-Jakob disease 248 Crick, Francis H. C. 84, 200 Cristae of mitochondria 14 Crossing-over 18 Crosslinking 79 Crotonase. See Enoyl hydratase Crowfoot Hodgkin, Dorothy M. 84 Cruciform structure in nucleic acids 229 Crustacea 24 Cruzain 619 Cryoenzymology 469 elastase 616 Cryoprotectants 191 Crystallins 169 Crystallography 131-137 electron 131 X-ray 132-137 Crystals, liquid 392-394 Crystal systems 133 Cubic symmetry... 

A cruciform. A nucleic acid molecule is shown in a cruciform structure. Two strands with complementary base sequence are shown with the backbones highlighted in purple, the individual bases are the short lines perpendicular to the backbones. Base pairing occurs wherever a base is shown joined to its partner. Note that both interstrand and intrastrand base pairing occur. 

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