A DNA sequence for positioning chromatosomes.

We have analysed the sequences of 280 chromatosomal DNA molecules. In approximately half the clones, a short DNA sequence of the preferred form NGGR is located at one, but not both, of the termini of the cloned DNA. We show that the clones lacking this signal possess a substantially stronger rotational positioning signal than those that contain it. These results indicate that the sequence organisation of chromatosomal DNA is asymmetric with respect to the midpoint and imply that the sequence NGGR may play a direct role in positioning chromatosomes in condensed chromatin.