Figure 1.

Clustered short DNA motifs recruit the DCC in C. elegans. It is proposed that the DCC (shown as the multicolored globular structure above the X chromosome (X)) recognizes and binds at four specific sites (rex-1, rex-2, rex-3 and rex-4) and then spreads or diffuses to the rest of the X chromosome. The rex sites have high densities of at least two degenerate DNA motifs (motif A, red; motif B, blue) and this clustering is required to bind the DCC. The same motifs occur on autosomes (A), but they are not clustered and thus do not bind the DCC.